Document:

<PAGE>   1
                                                                 EXHIBIT 10.8.3

                            THIRD AMENDMENT TO LEASE

         THIS THIRD AMENDMENT TO LEASE ("Third Amendment") is made this 10th day
of January, 2000, but shall be effective May 1, 1999, by and between TA/WESTERN,
LLC, a Delaware limited liability company as successor in interest
to THE EQUITABLE LIFE ASSURANCE SOCIETY OF THE UNITED STATES ("Landlord") and
VISUAL NETWORKS, INC., a Delaware corporation ("Tenant").

                              W I T N E S S E T H:

         WHEREAS, The Equitable Life Assurance Society of the United States,
Landlord's immediate predecessor in interest, and Tenant entered into that
certain Lease dated December 12, 1996, as amended by that certain Lease
Amendment dated September 2, 1997 (the "First Amendment) and as further amended
by that certain Second Lease Amendment dated February 8, 1999 (the "Second
Amendment) (collectively, the "Lease"), pursuant to which Tenant leased that
certain premises in the building located at 2092 Gaither Road, Rockville,
Maryland (the "Building"), said leased premises containing approximately Twenty
Eight Thousand Five Hundred Ninety Four (28,594) rentable square feet and
designated as Suites 110, 120, 150 and 200 (the "Original Premises"); and

         WHEREAS, Landlord and Tenant desire to amend the Lease (i) to extend
the term of the Lease; (ii) to increase the square footage of the Original
Premises; and (iii) to amend certain other terms and conditions of the Lease as
herein provided.

         NOW, THEREFORE, in consideration of the premises and mutual covenants
and agreements herein contained and for other good and valuable consideration,
the receipt and sufficiency of which are hereby acknowledged, Landlord and
Tenant hereby agree to the following:

         1.       RECITALS.  The recitals set forth above are incorporated
herein by this reference with the same force and effect as if fully set forth
hereinafter.

         2.       CAPITALIZED TERMS. Capitalized terms not otherwise defined
herein shall have the meaning ascribed to them in the Original Lease.

         3.       LANDLORD. All references in the Lease to The Equitable Life
Assurance Society of the United States, previously known as Landlord, shall now
apply to TA/Western, LLC which acquired the Building.

         4.       TERM.

                  a. ORIGINAL PREMISES. The Term of the Lease with respect to
the Original Premises is hereby extended for approximately five (5) years and
one (1) month, commencing December 1, 2001 (the "Renewal Date") through December
31, 2006 (inclusively, the "Renewal Term"), unless sooner terminated pursuant to
the Lease as amended hereby.

                  b. FOURTH EXPANSION PREMISES. The Term of the Lease with
respect to the Fourth Expansion Premises, as hereinafter defined, shall
commence, retroactively, on May 1, 1999 (the "Fourth Expansion Premises
Commencement Date") and shall be coterminous with the Term of the Lease with
respect to the Original Premises and, accordingly, shall expire on the
expiration date with respect to the Original Premises.

                                       1
<PAGE>   2

         5.       PREMISES.

                  a. Effective retroactively to January 1, 1999 (the "Third
Expansion Premises Commencement Date"), the Original Premises shall be increased
by Thirteen Thousand Four Hundred Fifty One (13,451) rentable square feet of
space on the second (2nd) floor of the Building designated as Suite 220 as shown
on Exhibit A attached hereto (the "Third Expansion Premises) (the Original
Premises and the Third Expansion Premises shall be referred to collectively as
the "Original Premises"). As of the Third Expansion Premises Commencement Date,
Section (b) of the Data Sheet ("Data Sheet") attached to the Lease and made a
part thereof; Section 1(m) of the Lease; Paragraph 1 of the First Amendment and
Paragraph 1 of the Second Amendment are hereby modified to reflect the rentable
square footage of the Premises to be Forty Two Thousand Forty Five (42,045)
rentable square feet.

                  b. Effective retroactively as of the Fourth Expansion Premises
Commencement Date, the Original Premises shall be additionally increased by
approximately Eleven Thousand Nine Hundred (11,900) rentable square feet of
space on the first (1st) floor of the Building which shall be known as Suite 100
as shown on Exhibit A-1 attached hereto and made a part hereof (the "Fourth
Expansion Premises") to approximately Fifty Three Thousand Nine Hundred Forty
Five (53,945) rentable square feet. As of the Fourth Expansion Premises
Commencement Date, Section (b) of the Data Sheet ("Data Sheet") attached to the
Lease and made a part thereof; Section 1(m) of the Lease; Paragraph 1 of the
First Amendment, Paragraph 1 of the Second Amendment and Paragraph 5.a. of this
Third Amendment are hereby further modified to reflect the rentable square
footage of the Premises to be Fifty Three Thousand Nine Hundred Forty Five
(53,945) rentable square feet.

                  c. From and after the Fourth Expansion Premises Commencement
Date, except as otherwise provided herein, all references in the Original Lease
and herein to: (i) "Premises" shall refer collectively to the Original Premises,
the Third Expansion Premises and the Fourth Expansion Premises; and (ii) "Lease"
shall be deemed to mean the Original Lease, as amended by the First Amendment,
the Second Amendment and this Third Amendment.

         6.       BASIC RENTAL

                  ORIGINAL PREMISES.

                  a. Effective as of the Fourth Expansion Premises Commencement
Date, Tenant shall pay Basic Rental for the Original Premises in the same manner
as set forth in Section 3 of the Lease in the following amounts:

<TABLE>
<CAPTION>
         PERIOD               BASIC RENTAL PSF             MONTHLY BASIC RENTAL                       ANNUAL BASIC RENTAL
<S>                           <C>                          <C>                                        <C>
05-01-99 to 09-30-99               $16.37                       $57,348.09                                $688,177.08
10-01-99 to 11-30-99               $16.37                       $57,348.09                                $688,177.08
12-01-99 to 02-28-00               $16.78                       $58,808.35                                $705,700.20
03-01-00 to 11-30-00               $16.86                       $59,068.53                                $708,822.36
12-01-00 to 02-28-01               $17.29                       $60,572.62                                $726,871.44
03-01-01 to 11-30-01               $17.36                       $60,840.60                                $730,087.20
12-01-01 to 11-30-02               $22.25                       $77,958.44                                $935,501.28
12-01-02 to 11-30-03               $22.92                       $80,297.19                                $963,566.28
12-01-03 to 11-30-04               $23.61                       $82,706.11                                $992,473.32
12-01-04 to 11-30-05               $24.31                       $85,187.29                               $1,022.247.48
12-01-05 to 12-31-06               $25.04                       $87,742.91                               $1,052,914.92
</TABLE>

                                       2
<PAGE>   3

                  FOURTH EXPANSION PREMISES.

                  b. As of the Fourth Expansion Premises Commencement Date, in
  addition to the payments of Basic Rental for the Original Premises as set
  forth herein above, Tenant shall pay Basic Rental for the Fourth Expansion
  Premises in the same manner as set forth in Section 3 of the Lease, in the
  following amounts:

<TABLE>
<CAPTION>
         PERIOD               BASIC RENTAL PSF             MONTHLY BASIC RENTAL                       ANNUAL BASIC RENTAL
<S>                           <C>                          <C>                                        <C>
05-01-99 to 09-30-99               $16.27                       $16,131.17                                $193,574.04
10-01-99 to 11-30-99               $21.00                       $20,825.00                                $249,900.00
12-01-99 to 02-28-00               $21.00                       $20,825.00                                $249,900.00
03-01-00 to 11-30-00               $21.00                       $20,825.00                                $249,900.00
12-01-00 to 02-28-01               $21.63                       $21,449.75                                $257,397.00
03-01-01 to 11-30-01               $21.63                       $21,449.75                                $257,397.00
12-01-01 to 11-30-02               $22.25                       $22,064.58                                $264,774.96
12-01-02 to 11-30-03               $22.92                       $22,726.52                                $272,718.24
12-01-03 to 11-30-04               $23.61                       $23,408.32                                $280,899.84
12-01-04 to 11-30-05               $24.31                       $24,110.57                                $289,326.84
12-01-05 to 12-31-06               $25.04                       $24,833.88                                $298,006.56
</TABLE>

                  c.       Section (d) of the Data Sheet and Sections 1(b), 3(d)
and 4 of the Lease are hereby deleted in their entirety.

         7.       TENANT'S PROPORTIONATE SHARE OF BUILDING.

                  a. As of the Third Expansion Premises Commencement Date
(January 1, 1999), the definition of Tenant's Proportionate Share as set forth
in Section (l) of the Data Sheet; Sections 1(u) and 1(v) of the Lease; Paragraph
5 of the First Amendment; and Paragraph 5 of the Second Amendment shall be
amended to increase Tenant's Proportionate Share from Fifty Three and 24/100
percent (53.24%) to Seventy Seven and 94/100 percent (77.94%);

                  b. As of the Fourth Expansion Premises Commencement Date (May
1, 1999), the definition of Tenant's Proportionate Share as set forth in Section
(l) of the Data Sheet; Sections 1(u) and 1(v) of the Lease; Paragraph 5 of the
First Amendment; Paragraph 5 of the Second Amendment and Paragraph 7a. of this
Third Amendment shall be further amended to increase Tenant's Proportionate
Share from Seventy Seven and 94/100 percent (77.94%) to One Hundred and 00/100
percent (100%);

         8.       BASE YEAR STOP.

                  a. As of the Renewal Date, Section 1 (d) of the Lease is
hereby amended by deleting Section 1 (d) in its entirety and substituting the
following in lieu thereof:

                     "Base Year Stop - Original Premises and Third Expansion
Premises": the Basic Cost incurred during the calendar year 2002 divided by the
number of rentable square feet in the Building."

                  b. As of the Fourth Expansion Premises Commencement Date (May
1, 1999), Section 1 (d) of the Lease is hereby modified by adding the following
at the end of Section 1 (d):

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<PAGE>   4

                     ""Base Year Stop - Fourth Expansion Premises":  the Basic
Cost incurred during the calendar year 2000 divided by the number of rentable
square feet in the Building."

         9.       TENANT'S OBLIGATIONS.

                  a. As of January 1, 2000, Tenant shall contract directly for
trash removal to or for the benefit of the Premises. As soon as reasonably
possible after December 31, 1999, Landlord shall calculate the per rentable
square foot trash removal cost incurred by Landlord during the calendar year
1999 (the "1999 Trash Removal Cost"), and shall reduce Tenant's Basic Rental, if
applicable, by an amount equal to the 1999 Trash Removal Cost, such reduction to
be retroactive to January 1, 2000;

                  b. As of January 1, 2000, Tenant shall contract directly for
security services to or for the benefit of the Premises. Commencing January 1,
2000, Landlord shall reduce Tenant's Basic Rental by an amount equal to five
cents ($.05) per rentable square foot of the Premises for the cost of security
services.

                  c. As soon as reasonably possible after December 31, 1999,
Landlord shall calculate the per rentable square foot electric cost incurred by
Landlord during the calendar year 1999 (the "1999 Electric Cost). Tenant shall
have thirty (30) days from receipt of the 1999 Electric Cost to either (i) cause
the electric services to or for the benefit of the Premises to be placed in
Tenant's name as the responsible party and Tenant shall directly pay to the
local utility company for the electric services to or for the benefit of the
Premises; or (ii) continue to pay for electric services to or for the benefit of
the Premises in accordance with applicable provisions of the Lease. In the event
Tenant elects sub-section (i) hereinabove, Landlord shall reduce Tenant's Basic
Rental, if applicable, by an amount equal to the 1999 Electric Cost, such
reduction to be retroactive to January 1, 2000.

                  d. Effective January 1, 2000, Tenant shall cause the water and
sewer invoices for the Premises to be placed in Tenant's name as the responsible
party and Tenant shall directly pay to the local utility company for the water
and sewer services to or for the benefit of the Premises. Commencing January 1,
2000, Landlord shall reduce Tenant's Basic Rental by an amount equal to seven
cents ($.07) per rentable square foot of the Premises for the cost of water and
sewer services.

         10.      TENANT IMPROVEMENTS.

                  a. TENANT IMPROVEMENTS WITH RESPECT TO THE ORIGINAL PREMISES.
In connection with Tenant's extending the Term of the Lease for the Renewal
Term, Tenant has completed certain improvements with respect to the Original
Premises (the "Original Premises Improvements"). Tenant hereby certifies that it
has filed all drawings and specifications, paid all fees and obtained all
permits and applications from any governmental authorities having jurisdiction,
obtained any certificates or approvals, including a certificate of occupancy,
required to enable Tenant to occupy the Original Premises, and obtained and
delivered to Landlord all necessary lien waivers in connection with the
construction of the Original Premises Improvements. In connection thereto,
Landlord shall grant to Tenant an "Original Premises Improvement Allowance" of
up to a total of Six and 25/100 Dollars ($6.25) per rentable square foot of
space in the Original Premises (i.e., 42,045 rentable square feet multiplied by
$6.25 = $262,781.25). Of the total Original Premises Improvement Allowance,
Three and 25/100 Dollars ($3.25) per rentable square foot of space in the
Original Premises (i.e. 42,045 rentable square feet multiplied by $3.25 =
$136,646.25) shall be disbursed by Landlord to Tenant on or before March 1, 2001
(the "First Disbursement"), and the remaining Three and 00/100 Dollars ($3.00)
per rentable square foot of space in the Original Premises (i.e. 42,045 rentable
square feet multipled by $3.00 = $126,135.00) shall

                                       4
<PAGE>   5

be disbursed by Landlord to Tenant on or before March 1, 2002 (the "Second
Disbursement").

                  b. TENANT IMPROVEMENTS WITH RESPECT TO THE FOURTH EXPANSION
PREMISES. Tenant shall construct improvements for the Fourth Expansion Premises
and Building, as applicable ("Fourth Expansion Premises Improvements") in
accordance with the Work Letter Agreement attached hereto as Schedule 1. In
connection thereto, Landlord hereby grants to Tenant a "Fourth Expansion
Premises Improvement Allowance" of up to Ten and 00/100 Dollars ($10.00) per
rentable square foot of space in the Fourth Expansion Premises (i.e., 11,900
rentable square feet multiplied by $10.00 = $119,000.00), which Fourth Expansion
Premises Improvement Allowance shall be used only for the items specified in the
Cost Breakdown, as that term is defined in Schedule 1. Landlord shall reimburse
to Tenant the Fourth Expansion Premises Improvement Allowance on or before April
1. 2000.

                  c. Tenant acknowledges that all obligations of Landlord
pursuant to Section 7 of the Lease pertaining to the Original Premises have been
met and Landlord shall have no obligation to construct any tenant improvements
to the Premises on behalf of Tenant.

         11.      BROKERS. Landlord and Tenant each represent and warrant to the
other that it has not had any dealings or entered into any agreements with any
person, entity, realtor, broker, agent or finder in connection with the
negotiation of this Third Amendment other than McShea & Company, Inc. and The
Fred Ezra Company (collectively, the "Brokers"). Landlord shall pay a commission
to the Brokers in accordance with the terms and conditions of a separate
agreement between Landlord and the Brokers. Landlord and Tenant each agree to
indemnify, defend and hold the other harmless from and against any loss, claim,
damage, expense (including costs of suit and reasonable attorneys' fees) or
liability for any compensation, commission or charges claimed by any such
unnamed realtor, broker, agent or finder claiming to have dealt with the
indemnifying party in connection with this Third Amendment.

         12.      REAFFIRMATION OF TERMS. All other terms, covenants and
provisions of the Original Lease are hereby confirmed and ratified and except as
modified herein, shall remain unchanged and in full force and effect.

         13.      REPRESENTATIONS. Landlord and Tenant each hereby represent and
warrant to the other that it (i) is not in default of any of its obligations
under the Original Lease and that such Original Lease is valid, binding and
enforceable in accordance with its terms, (ii) it has full power and authority
to execute and perform this Third Amendment, and (iii) it has taken all action
necessary to authorize the execution and performance of this Third Amendment.

         14.      COUNTERPART COPIES. This Third Amendment may be executed in
two or more counterpart copies, each of which shall be deemed to be an original
and all of which counterparts shall have the same force and effect as if the
parties hereto had executed a single copy of this Third Amendment.

                         [SIGNATURES ON FOLLOWING PAGE]

                                       5
<PAGE>   6

         IN WITNESS WHEREOF, Landlord and Tenant have executed this Third
Amendment as of the day and year first above written.

                           LANDLORD:

                           TA/Western, LLC, a Delaware limited liability company

                           By:      Realty Associates Advisors LLC, a Delaware
                                    limited liability company, manager

                                    By:      Realty Associates Advisors Trust,
                                             a Massachusetts business trust,
                                             sole member

                                             By:  HENRY G. BRAUER
                                                  ---------------------
                                             Its:  Regional Director
                                                   ----------------------
                           TENANT:

                           VISUAL NETWORKS, INC., a Delaware corporation

                           By: PETER J. MINIHANE
                              -----------------------------
                           Its: Executive Vice President,
                               ----------------------------
                               Chief Financial Officer and
                               Treasurer

                                       6
<PAGE>   7

                                    EXHIBIT A

                            THIRD EXPANSION PREMISES

                                       A-1

<PAGE>   8

                                   EXHIBIT A-1

                            FOURTH EXPANSION PREMISES

                                      A1 1
<PAGE>   9

                                   SCHEDULE 1

                              WORK LETTER AGREEMENT

1.       Plans.

         Tenant shall cause its architects and engineers to prepare and submit
to Landlord for approval detailed plans, specifications and working drawings
("Plans") for the construction of the Fourth Expansion Premises Improvements to
the Fourth Expansion Premises and Building, as applicable, which such approval
shall not be unreasonably withheld. Landlord reserves the right to reasonably
approve any space planner, architect or engineer employed by Tenant. Tenant's
Plans shall include items and information as Landlord shall reasonably require
to evaluate Tenant's work. Tenant shall use the Plans to obtain all permits and
approvals which are necessary to construct the Fourth Expansion Premises
Improvements. All Fourth Expansion Premises Improvements shall be constructed in
a good and workmanlike manner and in accordance with all applicable laws, codes
and regulations, including the Americans with Disabilities Act ("ADA"). It is
expressly agreed that (a) Tenant shall not commence any such work until said
Plans have been approved by Landlord, and (b) the Plans which have been so
approved by Landlord shall be used by Tenant to obtain all permits that are
necessary to construct the Fourth Expansion Premises Improvements. As used
herein, the term "Fourth Expansion Premises Improvements " shall include all
work to be done in the Fourth Expansion Premises pursuant to the Plans,
including, but not limited to: demolition work, partitioning, doors, ceiling,
floor coverings, wall finishes (including paint and wallcoverings), window
coverings, electrical (excluding the cost of computer cabling, Tenant's
telephone system and wiring, and any other special electrical or wiring
dedicated to Tenant's operations or business), plumbing, heating, ventilating
and air conditioning, fire protection, cabinets and other millwork. After
approval of the Plans by Landlord, no further material changes to the Plan shall
be made without the prior written approval of Landlord which such approval shall
not be unreasonably withheld. Tenant acknowledges that Landlord's review and
approval of the Plans is not conducted for the purpose of determining the
accuracy and completeness of the Plans, their compliance with applicable codes
and governmental regulations including ADA, or their sufficiency for purposes of
obtaining a building permit, all of which shall remain the responsibility of
Tenant and Tenant's architect. Accordingly, Landlord shall not be responsible
for any delays in obtaining the building permit due to the insufficiency of the
Plans or any delays due to changes in the Plans required by the applicable
governmental regulatory agencies reviewing the Plans.

2.       Fourth Expansion Premises Improvement Allowance.

         Tenant shall provide Landlord with a breakdown of the estimated total
cost of the Fourth Expansion Premises Improvements ("Cost Breakdown"). Landlord
hereby grants to Tenant an "Fourth Expansion Premises Improvement Allowance" of
up to Ten and 00/100 Dollars ($10.00) per rentable square foot of space in the
Fourth Expansion Premises (i.e., 11,900 rentable square feet multiplied by
$10.00 = $119,000.00) which Fourth Expansion Premises Improvement Allowance
shall be used only for the items specified in the Cost Breakdown. The Fourth
Expansion Premises Improvement Allowance shall be disbursed to Tenant not more
frequently than once per month based on disbursement requests submitted by
Tenant to Landlord and certified by Tenant's architect. Such disbursement
request shall set forth the total amount incurred, expended and/or due for each
requested item less prior disbursements and a description of the work performed,
and materials supplied and/or costs incurred or due with respect to each item
for which disbursement is requested. Each such disbursement request shall be
accompanied by invoices, vouchers, statements, affidavits, payroll records
and/or other documents reasonably requested by Landlord, which substantiate
costs incurred to justify such a disbursement, together with lien waivers for
those contractors and materialmen providing construction services or materials.
In addition, each disbursement shall be subject to inspection and approval of
completed work by

                                    Sch 1-1
<PAGE>   10

Landlord's construction engineer, which such approval shall not be unreasonably
withheld, conditioned or delayed. In the event the Cost Breakdown exceeds the
Fourth Expansion Premises Improvement Allowance, Tenant shall pay from another
source of funds the amount by which the Cost Breakdown exceeds the Fourth
Expansion Premises Improvement Allowance prior to any disbursement of the Fourth
Expansion Premises Improvement Allowance by Landlord. If, at any time during the
construction of the Fourth Expansion Premises Improvements, the total amount
remaining to be paid for Fourth Expansion Premises Improvements exceeds the
amount of the Fourth Expansion Premises Improvement Allowance remaining to be
disbursed, at Landlord's option, no further disbursement of the Expansion
Premises Improvement Allowance shall be made by Landlord unless, and until
Tenant has expended such sums as to cause the Fourth Expansion Premises
Improvement Allowance to again be sufficient to pay each of the remaining costs.
In the event the actual cost of the Fourth Expansion Premises Improvements is
less than the Fourth Expansion Premises Improvement Allowance, the unused
portion of the Fourth Expansion Premises Improvement Allowance shall not be paid
or refunded to Tenant or be available to Tenant as credit against any
obligations of Tenant under the Lease. Notwithstanding the foregoing, Landlord
shall reimburse to Tenant the Fourth Expansion Premises Improvement Allowance by
no later than April 1, 2000.

3.       Construction of Fourth Expansion Premises Improvements.

         3.1      Landlord hereby approves Coakley Williams Construction Company
as Tenant's contractor. Landlord's approval, when required in this Work Letter
Agreement, shall be given or denied (as applicable) within five (5) business
days of receipt of the necessary information from Tenant. Tenant's contractors
and subcontractors shall be required to provide the following types of
insurance, in the minimum amounts indicated, naming Landlord (and Landlord's
mortgagee, if required by Landlord) as additional insured:

          (a)     Workmen's Compensation with full statutory limits for
                  employer's liability.

          (b)     Commercial General Liability Insurance including direct and
                  contingent liability in the aggregate amount of One Million
                  and No/100 Dollars ($1,000,000.00) combined single limit
                  coverage per occurrence for personal injury, death or property
                  damage.

          (c)     The Liability Policy shall include coverage for Broad Form
                  Hold Harmless Agreement as is contained in the standard
                  contract.

          (d)     Automobile Liability insurance with bodily injury limits of
                  $250,000 per person, $500,000 per accident, and $50,000 per
                  accident for Property Damage.

Certificates of all of the foregoing insurance shall be delivered to Landlord
before construction of the Improvements is started and before Tenant's
contractor's equipment is placed upon the Premises. In all other respects, the
insurance coverage above mentioned shall comply with the Lease provisions.

         3.2      It is agreed that Tenant assumes the entire responsibility and
liability due to its negligence, including statutory or common law, for any and
all injuries or death of any or all persons, including its contractor,
subcontractors and employees, and for any and all damages to property caused by
or resulting from or arising out of any act or omission on the part of Tenant,
its contractor, subcontractors or employees, in the prosecution of the work
thereunder other than those arising out of the gross negligence or willful
misconduct of Landlord, its agents or employees. With respect to such work
Tenant agrees to indemnify and save harmless Landlord, its mortgagee, architect,
engineers and their employees and all other tenants of the Property from and
against all losses and expense, including legal fees, which they may suffer or
pay as the result of claims or lawsuits due to, because of or arising out of any
and all such injuries, death or

                                    Sch 1-2
<PAGE>   11

damage, whether real or alleged, and Tenant, its contractor and subcontractors
shall assume and defend at their own expense all such claims or lawsuits. Tenant
agrees to insure this assumed liability in its Comprehensive General Liability
Policy and the original or copy of the policy delivered to Landlord shall
indicate this contractual coverage.

         3.3      For and during the period of construction, Tenant shall
provide and pay for all utilities consumed upon the Fourth Expansion Premises
during said period and for the removal of all temporary connections.

         3.4      Upon completion of the Fourth Expansion Premises Improvements,
Tenant's contractors and/or subcontractors shall provide Landlord, without cost
to Landlord, with one (1) set of transparent "as built" drawings.

         3.5      Completion. Tenant shall endeavor to cause the contractor to
substantially complete construction of the Fourth Expansion Premises
Improvements in a diligent manner. It shall be the sole responsibility of Tenant
to file all drawings and specifications, pay all fees and obtain all permits and
applications from any governmental authorities having jurisdiction, and to
obtain any certificates or approvals, including a certificate of occupancy,
required to enable Tenant to occupy the Fourth Expansion Premises. Landlord
shall not be liable for any loss or damages as a result of delays in
construction of the Fourth Expansion Premises Improvements. No delay in
completion of construction of the Fourth Expansion Premises Improvements shall
delay the Commencement Date of the Lease or otherwise effect Tenant's obligation
to pay Basic Rental beyond the date specified in the Third Amendment.

4.       Incorporation. This Agreement is and shall be incorporated by reference
in the Lease, and all of the terms and conditions of the Lease are and shall be
incorporated herein by this reference.

                                    Sch 1-3<PAGE>   1
                                                                   EXHIBIT 10.9

                                   SUBLEASE

            THIS SUBLEASE (this "Sublease") is dated for reference purposes
as of October 1, 1999, and is made by and between Micron Technology, Inc., a
Delaware corporation ("Sublessor"), and Visual Networks, Inc., a Delaware
corporation ("Sublessee"). Sublessor and Sublessee agree as follows:

            1.    Recitals.  Metropolitan Life Insurance Company, as Landlord
("Master Lessor"), and Mitsubishi Electronics America, Inc. ("Master
Sublessor") entered into that certain Office Lease dated as of December 19,
1997 ("Master Lease"), with respect to that certain 32,256 square feet of
space ("Premises") located in that approximately 79,776 square foot building
("Building") commonly known as 999 East Arques Avenue, Sunnyvale,
California. Master Sublessor also entered into a sublease with Rendition,
Inc. ("Rendition") dated December 19, 1997 ("Underlease"). Sublessor acquired
the stock of Rendition in October of 1998 and thereby assumed Rendition's
obligations and liabilities under the Underlease. A copy of the Master Lease
is attached hereto as Exhibit A. A copy of the Underlease is attached hereto
as Exhibit B. Capitalized terms used and not otherwise defined herein shall
have the meaning ascribed to them in the Master Lease. Sublessor desires to
lease to Sublessee and Sublessee desires to lease from Sublessor the Premises
which are depicted on Exhibit A to the Master Lease.

            2.    Premises.  Subject to the terms and conditions set forth
herein, Sublessor subleases to Sublessee, and Sublessee subleases from
Sublessor, the Premises.

            3.    Term/Early Occupancy.  Subject to Paragraph 16, the term
("Term") of this Sublease shall commence on the later of (a) thirty (30) days
following the date Sublessor vacates the Premises; or (b) December 1, 1999
("Commencement Date"), unless otherwise agreed to in writing by the parties.
This Sublease shall terminate on the earliest to occur of (a) July 31, 2003
(the "Expiration Date") or (b) the date this Sublease is sooner terminated
pursuant to its terms . Sublessor agrees to cooperate with Sublessee to allow
Sublessee access to the Premises, if possible, prior to the Commencement Date
("Early Occupancy Period") to allow Sublessee to install improvements in the
Premises. During such Early Occupancy Period, Sublessee shall be subject to
all of the terms and conditions of this Sublease excluding the payment of any
Base Rent or Operating Expenses.

            4.    Delivery and Acceptance.  If Sublessor is unable to deliver
possession of the Premises to Sublessee on or before February 28, 2000, for any
reason whatsoever, then, as Sublessee's sole and exclusive remedy, Sublessee may
terminate this Sublease by written notice to Sublessor given on or before March
10, 2000, whereupon any monies previously paid by Sublessee to Sublessor shall
be reimbursed to Sublessee and the parties shall have no further obligation to
each other. Except as expressly set forth otherwise herein, by taking possession
of the Premises, Sublessee conclusively shall be deemed to have accepted the
Premises in their "as-is", then-existing condition, without any warranty
whatsoever of Sublessor with respect thereto.

<PAGE>   2

            5.    Rent.

                  A.    Base Rent.  During the Term, Sublessee shall pay to
Sublessor as base monthly rent ("Base Rent") the following amounts:

<TABLE>
<CAPTION>
             Months                  Base Rent
             ------                  ---------
<S>                                <C>
             Prior to 11/30/99       $60,673.54
             12/l/99-11/30/00        $63,403.85
             12/l/00-11/30/01        $66,257.02
             12/l/01-11/30/02        $69,238.58
             12/l/02-7/31/03         $72,354.32
</TABLE>

            Base Rent and any Rent Adjustment Deposit (as defined below) of
which Sublessee has at least ten (10) days' prior written notice shall be
paid to Sublessor on or before the first (1st) day of each month during the
Term.  Base Rent and Additional Rent (as defined below) (collectively,
"Rent") for any period during the Term hereof which is for less than one
month of the Term shall be a pro rata portion of the monthly installment
based on a calendar month. Base Rent and any Rent Adjustment Deposit of which
Sublessee has at least ten (10) days' prior written notice shall be payable
without notice or demand, and Rent shall be paid without, any deduction,
offset, or abatement, in each case in lawful money of the United States of
America. Rent shall be paid directly to Sublessor at Micron Technology, Inc.,
8000 South Federal Way, Boise, Idaho 83716 - Attention: Real Estate Manager,
or such other address as may be designated in writing by Sublessor.
Notwithstanding the foregoing, upon execution of this Sublease by Sublessee,
Sublessee shall pay to Sublessor the sum of Sixty-Three Thousand Four Hundred
and Three Dollars and 85/00 ($63,403.85) as prepayment of rent for credit
against the first installment of Base Rent due hereunder and any resulting
excess shall be applied to the second installment of Base Rent due hereunder.

                  B.    Additional Rent.  Sublessee shall pay to Sublessor
within ten (10) days of written demand by Sublessor to Sublessee (which
written demand shall include any landlord statement or invoice required or
provided for under the Master Lease), all expenses under the Master Lease
that are applicable to the Premises and required to be paid by Sublessor to
Master Lessor, or otherwise required to be paid by Sublessor under the Master
Lease, including, without limitation, all (i) Rent Adjustments, Rent
Adjustment Deposits, utility charges and insurance premiums, (ii) all taxes
and assessments payable by Sublessor pursuant to Article Four of the Master
Lease, and (iii) Sublessor's share of Master Lessor's property insurance
premiums payable pursuant to the Master Lease ("Additional Rent").

            6.    Security Deposit.  Upon execution of this Sublease by
Sublessee, Sublessee shall deposit with Sublessor the sum of Seventy-Two
Thousand Three Hundred and Fifty-Four Dollars and 32/00 ($72,354.32), in
cash, as security for the performance by Sublessee of the terms and
conditions of this Sublease. If Sublessee fails to pay Rent or other charges
due in accordance with the terms of this Sublease or otherwise defaults with
respect to any provision of this Sublease, then Sublessor may draw upon, use,
apply or retain all or any portion of the

                                       2
<PAGE>   3

Security Deposit for the payment of any Rent or other charge in default, for the
payment of any other sum which Sublessor has become obligated to pay by reason
of Sublessee's default, or to compensate Sublessor for any loss or damage which
Sublessor has suffered thereby. If Sublessor so uses or applies all or any
portion of the Security Deposit, then Sublessee, within ten (10) days after
written demand by Sublessor therefor, shall deposit cash with Sublessor in the
amount required to restore the Security Deposit to the full amount stated above.
Within thirty (30) days following the expiration or earlier termination of this
Sublease, if Sublessee is not in default hereunder, Sublessor shall return to
Sublessee so much of the Security Deposit as has not been applied by Sublessor
pursuant to this paragraph, or which is not otherwise required to cure
Sublessee's defaults hereunder.

            7.    Condition of the Premises.  Sublessor shall provide the
Premises in "broom clean" condition with Sublessor's personal property and
equipment removed (except as otherwise agreed to by Sublessee) and all
operating systems in good condition. Except as set forth in the preceding
sentence, Sublessee is subleasing the Premises on an "as-is" basis, and
Sublessor has made no representations or warranties, express or implied, with
respect to the condition of the Premises as of the Commencement Date.
Sublessor shall have no obligation whatsoever to make or pay the cost of any
alterations, improvements or repairs to the Premises, including, without
limitation, any improvement or repair required to comply with any law,
regulation, building code or ordinance (including, without limitation, the
Americans with Disabilities Act of 1990). Sublessor shall have no obligation
to perform any of the repairs (or capital improvements) required by Master
Lessor under the terms of the Master Lease.

            8.    Effect of Conveyance.  Sublessor shall not assign or
transfer its interest under the Under Lease without all required consents of
the Master Lessor and the Master Sublessor.  In the event of any permitted
assignment or transfer of such interest, as between Sublessor and Sublessee,
Sublessor shall be and hereby is entirely relieved of all covenants and
obligations of Sublessor hereunder, provided that the assignee or transferee
agrees in writing for the benefit of Sublessee to assume and carry out all
covenants and obligations of Sublessor hereunder, whether arising before or
after such assignment or transfer.  Sublessor shall transfer and deliver any
security of Sublessee to the assignee or transferee, and thereupon Sublessor
shall be discharged from any further liability with respect thereto.

            9.    Use.  Sublessee shall use the Premises for office, research
and development and any other uses permitted under the Master Lease.

            10.   Surrender.  Prior to expiration or earlier termination of
this Sublease, Sublessee shall remove all trade fixtures, personal property
and alterations to the Premises made by Sublessee that Sublessee is required
to remove or has the right to remove pursuant to the terms of the Master
Lease, and shall surrender the Premises to Sublessor in good condition, free
of Hazardous Materials caused by Sublessee, reasonable wear and tear,
casualties and condemnation, excepted. If the Premises are not so
surrendered, then Sublessee shall be liable to Sublessor for all costs
incurred by Sublessor (including any charges by Master Lessor under the
Master Lease) in returning the Premises to such required condition.

                                       3
<PAGE>   4

            11.   Holdover.  If Sublessee remains in possession of the
Premises after the expiration or earlier termination of this Sublease,
Sublessee's continued possession shall be as a sublessee at sufferance of
Sublessor and Sublessee shall continue to comply with and perform all the
terms and obligations of the Sublessee under this Sublease and pay Sublessor
holdover Base Rent equal to one hundred fifty percent (150%) of the Base Rent
payable immediately preceding the termination of this Sublease. Sublessee
shall indemnify, protect, defend and hold harmless Sublessor, its officers,
directors, employees, agents and assigns, from and against loss and liability
resulting from Sublessee's delay in surrendering the Premises.

            12.   Other Sublease Terms.

                  A.    Incorporation By Reference.  Except as otherwise
provided in or modified by this Sublease, the terms, and conditions contained
in the Master Lease are incorporated herein by reference, and are made a part
hereof as if set forth herein at length; provided, however, that:  (i) each
reference in such incorporated sections to "Lease" shall be deemed a
reference to "Sublease"; (ii) each reference to the "Premises" shall be
deemed a reference to the "Premises" as defined herein; (iii) each reference
to "Landlord" and "Tenant" shall be deemed a reference to "Sublessor" and
"Sublessee", respectively; (iv) Sublessor shall have no liability to
Sublessee with respect to (a) representations and warranties made by Master
Lessor under the Master Lease and (b) subject to Sublessor's obligations
under Section 12.E. and F. hereof, Master Lessor's repair, maintenance,
restoration, upkeep, insurance and similar obligations under the Master
Lease, regardless of whether the incorporation of one or more provisions of
the Master Lease into the Sublease might otherwise operate to make Sublessor
liable therefor; (v) with respect to any obligation of Sublessee to be
performed under this Sublease, wherever the Master Lease grants to Sublessor
a specified number of days to perform its corresponding obligations under the
Master Lease (excluding the payment of Monthly Base Rent or any other sum for
which notice from Sublessor to Sublessee is required hereunder), Sublessee
shall have two (2) fewer days to perform the obligation, including without
limitation, curing any defaults (which cure period shall automatically
commence to run against Sublessee at the same time it commences to run
against Sublessor provided that Sublessor immediately provides Sublessee with
a copy of Master Lessor's or Master Sublessor's notice of default, if Master
Lessor or Master Sublessor has not already done so); (vi) with respect to any
approval or consent required to be obtained from the "Landlord" under the
Master Lease, such approval or consent must be obtained from Master Lessor,
Master Sublessor and Sublessor, and the approval or consent of Sublessor may
be withheld if Master Lessor's approval or consent is not obtained; and (vii)
the following provisions of the Master Lease are expressly NOT incorporated
herein by reference:  Section 1.01(2), (3), (4), (5), (6), (7), (11), (14);
Section 1.03(7) and (23), Section 2.02, Section 2.03, Section 2.05, Article
21, Article 22, Article 24, Exhibit B, Rider 1 and Rider 4.

                  B.    Incorporation of Underlease.  This Sublease shall
include all of the provisions of the Underlease, which are incorporated into
this Sublease as if fully set forth herein, except as modified in this
paragraph and except that: (i) each reference in such incorporated sections
to "Sublease" shall be deemed a reference to this Sublease; and (ii) each
reference to "Sublessor" in the Underlease shall be deemed a referenced to
Sublessor hereunder and each reference to "Sublessee" in the Underlease shall
be deemed a reference to "Sublessee," hereunder, except as otherwise
expressly set forth herein. Notwithstanding the foregoing, the

                                       4
<PAGE>   5

following provisions of the Underlease are expressly NOT incorporated herein by
reference: paragraphs 1, 2, 3, 4, 5, 6, 7.1, 7.2, 7.3 (except as may be modified
by this Sublease), 8, 9 and 10.

                  C.    Assumption of Obligations.  This Sublease is and at
all times shall be subject and subordinate to the Master Lease and the rights
of Master Lessor thereunder. Sublessor shall not commit or permit any of its
employees or agents to commit on the Premises any act or omission which shall
violate any term or condition of the Master Lease. Sublessee hereby expressly
assumes and agrees: (i) to comply with all provisions of the Master Lease
which are required to be performed by Sublessee hereunder; and (ii) to
perform all the obligations on the part of the "Tenant" to be performed under
the terms of the Master Lease during the term of this Sublease which are
required to be performed by Sublessee hereunder. Sublessee shall not commit
or permit to be committed on the Premises any act or omission which shall
violate any term or condition of the Master Lease.

                  D.    Rights and Benefits Under Master Lease and
Underlease.  Sublessee shall have all the rights, privileges and benefits
granted to or conferred upon Sublessor under the Master Lease and the
Underlease, provided that Sublessee's exercise of such rights, privileges and
benefits shall not cause Sublessor to be in default.

                  E.    Enforcement by Sublessee.  If Master Lessor shall
fail or refuse to comply with any of the terms of the Master Lease, or Master
Sublessor shall fail or refuse to comply with any of the terms of the
Underlease, Sublessee shall have the right, upon notice to Sublessor, to
exercise, in its own name, and that of Sublessor, all the rights available to
Sublessor under the Master Lease and the Underlease to enforce performance on
the part of Master Lessor and Master Sublessor, provided, however, that
Sublessee shall defend, indemnify and hold harmless Sublessor from and
against any costs and expenses arising out of or incurred in connection with
Sublessee's exercise of such rights.

                  F.    Enforcement by Sublessor.  If, notwithstanding the
provisions of Paragraph 12.E. above, Sublessee shall reasonably require the
participation of Sublessor in enforcing the obligations of Master Lessor
under the Master Lease, or Master Sublessor under the Underlease, then,
Sublessor, upon Sublessee's written request, shall endeavor diligently to
enforce such obligations (including the commencement of appropriate legal
proceedings) to attempt to cause Master Lessor or Master Sublessor to provide
Sublessee with the service or other benefit in question.  Sublessee shall
reimburse all reasonable costs and expenses Sublessor shall incur in
enforcing or attempting to enforce the Master Lease against Master Lessor,
and the Underlease against Master Sublessor.

                  G.    Preservation of Master Lease and Underlease.  So long
as Sublessee complies with its obligations under this Sublease:  (a)
Sublessor shall preserve the Underlease and keep the Underlease in full force
and effect throughout the Term and shall not, by voluntary agreement,
terminate the Underlease; (b) Sublessor shall not agree to any amendment of
the Master Lease or the Underlease in a manner that would have an adverse
impact on the rights or obligations of Sublessee under this Sublease without
the consent of Sublessee (which consent, in the event that the amendment
would have an adverse impact on the rights or obligations of Sublessee, may
be granted or denied at the sole discretion of Sublessee); (c) Sublessor
shall not, without Sublessee's written consent, exercise any right to

                                       5
<PAGE>   6

terminate the Underlease (including any right to treat the Underlease as
terminated pursuant to any bankruptcy or insolvency proceeding effecting
Master Sublessor) with respect to any period within the Sublease Term, other
than on account of casualty or condemnation (provided that Sublessee shall
defend, protect, hold harmless and indemnify Sublessor from and against any
additional costs and expenses that are incurred by Sublessor as a result of
Sublessor's waiver of its right to terminate the Underlease as provided
herein) and (d) Sublessor shall make prompt payment to the Master Lessor or
the Master Sublessor, as appropriate, of all sums paid by Sublessee to
Sublessor hereunder.

                  H.    Notices to or from Master Lessor or Master
Sublessor.  Each party shall  provide to the other with a copy of any notice
or other written communication of any kind given to or received from Master
Lessor or Master Sublessor, within one (1) business day following the
delivery or receipt of such notice or written communication.

                  I.    Encumbrance of Sublessor's Leasehold Estate.
Notwithstanding anything to the contrary in the Master Lease or the
Underlease, Sublessor shall not have the right to encumber its leasehold
estate during the Term.

            13.   Broker.  Sublessor and Sublessee each represent to the
other that they have not dealt with any real estate brokers, finders, agents
or salesmen in connection with this transaction except Colliers
International, Inc. ("Colliers") representing Sublessor and Wayne Mascia
Associates representing Sublessee (collectively "Brokers"). Each party agrees
to hold the other party harmless from and against all claims for brokerage
commissions, finder's fees or other compensation made by any other agent,
broker, salesman or finder as a consequence of said party's actions or
dealings with such agent, broker, salesman, or finder. Broker's fees shall be
paid by Sublessor pursuant to a separate agreement between Sublessor and
Colliers.

            14.   Notices. The address of each party shall be that address
set forth below their signatures at the end of this Sublease. Any party
hereto may change its address for the purposes of this Paragraph 14 by
delivery of at least five (5) days prior written notice of such change to
each other party in the manner set forth in this Paragraph. All notices,
demands or communications in connection with this Sublease shall be (i) in
writing, (ii) properly addressed, and (iii) either (a) served personally, (b)
sent by prepaid, certified mail, return receipt requested, (c) sent by
recognized overnight courier service, or (d) sent by facsimile, if to
Sublessor to "Real Estate Manager" and to "General Counsel" at the address
and fax numbers set forth below and if to Sublessee to "Property Manager" at
the address and fax numbers set forth below. Notices served personally shall
be deemed received on the date of delivery. Notices mailed in accordance
herewith shall be deemed received on the date the U.S. Post Office receipts
delivery or refusal to accept delivery. Notices delivered by recognized
courier service shall be deemed received on the next business day following
deposit with the courier- service. Notices sent by facsimile shall be deemed
received upon electronic confirmation of receipt of transmission. If a notice
is received or deemed received on a Saturday, Sunday or legal holiday, it
shall be deemed received on the next business day. All notices given to
Master Lessor under the Master Lease shall be considered received only when
delivered in accordance with the Master Lease.

            15.   Hazardous Materials.  Sublessee shall use no Hazardous
Materials (other than those listed on the attached Exhibit B hereto) in, on,
under or about the Premises or the

                                       6
<PAGE>   7

Building, except for normal types and quantities of Hazardous Materials
typically used in connection with the use of real property for general office
and administrative purposes, which Sublessee may use, in compliance with all
applicable laws and regulations, on the Premises.

            16.   Conditions Precedent.  Notwithstanding anything to the
contrary set forth in this Sublease, it shall be an express condition
precedent to Sublessor's obligations hereunder that, and this Sublease shall
not be effective unless and until: (i) Master Lessor  has consented in
writing to this Sublease; and (ii) Master Sublessor has provided its consent
in writing to this Sublease and such consent contains substantially the same
convenants from Master Sublessor with respect to the Master Lease that
Sublessor has made with respect to the Underlease in Paragraph 12.G. hereof.
If either Master Lessor or Master Sublessor do not consent in writing to this
Sublease within thirty (30) days after Sublessor's execution of this
Sublease, then Sublessor or Sublessee may, at any time thereafter until such
approval is obtained, terminate this Sublease upon written notice to the
other party, whereupon any monies previously paid by Sublessee to Sublessor
shall be reimbursed to Sublessee.

            17.   Assignment and Subletting.  Sublessee shall not assign this
Sublease or sublet all or any part of the Premises without both the prior
written consent of Sublessor, the Master Sublessor and the Master Lessor,
under the terms and conditions of the Master Lease. Any transfer circumstance
or event which constitutes an assignment or subletting under the Master Lease
shall constitute an assignment or subletting under this Sublease.

            18.   Parking.  Sublessee shall be entitled to all the parking
spaces available to the 999 E. Arques address, as specified in the Master
Lease.

            19.   Sublessee's Indemnity.  Sublessee shall indemnify, defend,
protect, and hold Sublessor and its officers, agents and employees
(collectively, "Sublessor's Agents") harmless from and against all claims,
demands, actions, causes of action, losses and expenses (collectively
"Claims") which may be brought against Sublessor or Sublessor's Agents or
which Sublessor or Sublessor's Agents may pay or incur by reason of any
breach or default of this Sublease by Sublessee, or the acts, omissions,
negligence or willful misconduct of Sublessee or Sublessee's employees,
agents, contractors, or invitees in or about the Premises during the Term to
the extent that the Claims are not caused by the negligence or willful
misconduct of Sublessor or Sublessor's Agents. Without limiting the
generality of the foregoing, Sublessee shall indemnify, defend, protect and
hold Sublessor and Sublessor's Agents harmless from and against any Claims
which may be brought against Sublessor or Sublessor's Agents or which
Sublessor or Sublessor's Agents may pay or incur by reason of any violation
of any laws by Sublessee or its employees, agents or contractors during the
term of the Sublease.

            20.   Successors.  This Sublease shall be binding on and inure to
the benefit of the parties hereto and their respective successors and
permitted assigns.

            21.   Counterparts.  This Sublease may be executed in one or more
counterparts each of which shall be deemed an original but all of which
together shall constitute one and the same instrument. Signature copies may
be detached from the counterparts and attached to a single copy of this
Sublease physically to form one document. A facsimile counterpart signature

                                       7
<PAGE>   8

delivered to each party shall be deemed an original for the purpose of the
execution of this Sublease.

            22.   No Conflict.  In the event of any conflict between the
terms of this Sublease and the terms of the Master Lease, as between
Sublessor and Sublessee, the terms of this Sublease shall prevail.

            23.   Quiet Enjoyment.  So long as Sublessee pays the rent and
performs its obligations under this Sublease (including the Master Lease or
Under Lease as incorporated by reference), Sublessor shall take no action, or
fail to take any action, which would interfere with the right of Sublessee to
peaceably have, hold and enjoy the Premises during the Term, subject to the
terms of the Master Lease or Under Lease and this Sublease.

            24.   Indemnity.  Sublessor and Sublessee shall each indemnify
and hold the other harmless from and against any and all loss, liability or
expense, including reasonable attorneys' fees, incurred or suffered by the
other party on account of the indemnifying party's failure to perform its
obligations, or because of a material breach by the indemnifying party under
this Sublease (including the Master Lease or Under Lease as incorporated by
reference) or the indemnifying party's intentionally wrongful acts.

            25.   Entire Agreement.  This Sublease and the provisions of the
Master Lease and the Under Lease incorporated herein by the express terms of
this Sublease constitute the complete and exclusive agreement among the
parties with respect to the matters contained herein and supersede all prior
written or oral agreements or statements by and among the parties hereto,
provided that this Sublease shall be at all times subject to all of the terms
and conditions of the Master Lease and the Under Lease.

            IN WITNESS WHEREOF, the parties have executed this Sublease as of
the day and year first above written.

SUBLESSEE:                              SUBLESSOR:

VISUAL NETWORKS, INC.                   MICRON TECHNOLOGY, INC.
a Delaware corporation                  a Delaware corporation

By:           /s/ PETER J. MINIHANE     By:          /s/ STEVEN STOUT
              -----------------------                --------------------------
Printed Name: Peter J. Minihane         Printed Name: Steven Stout
              -----------------------                --------------------------
Its:          Executive Vice President, Its:         Vice President of
              CFO and Treasurer                        Facilities
              -----------------------                --------------------------
Date:         October 29, 1999          Date:        December 9, 1999
              -----------------------                --------------------------
Address:      2092 Gaither Road         Address:     8000 South Federal Way
              Rockville, Maryland 20850              Boise, Idaho 83707

                                       8
<PAGE>   9

Facsimile: (301) 296-2308                       (208) 368-2536

(note if different facsimile for different notice recipients)

                                       9
<PAGE>   10

                                  EXHIBIT A

                                 MASTER LEASE

                               (To be inserted)

<PAGE>   11

                                    EXHIBIT B

                                   UNDERLEASE

                                (To be inserted)

<PAGE>   12

                                    EXHIBIT C

                            HAZARDOUS MATERIALS USAGE

      Name        Volume Stored on Premises     Amount Used on a Monthly Basis
      ----        -------------------------     ------------------------------

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