<PAGE>


                                                                   EXHIBIT 10.16

                                      LEASE

        THIS AGREEMENT, made and entered into on March 21, 2002, by and between
DTS Commercial Interiors, Inc., a Florida corporation, hereinafter called
Landlord, and Invisa, Inc., a Nevada corporation, hereinafter called Tenant;

                                   WITNESSETH:

        That for and in consideration of the mutual covenants hereinafter
contained and the sums of money paid and hereinafter agreed to be paid by Tenant
to Landlord and for other valuable considerations, Landlord does hereby demise
and lease unto Tenant and Tenant does hereby hire and let from Landlord
commencing April 1, 2002, the following described property situate in Sarasota
County, Florida.

        The property located on Lots 16 and 17, Northgate Center Subdivision,
        Unit Number 4, as per plat thereof recorded in Plat Book 30, Pages 46
        and 46A, Public Records of Sarasota County, Florida, together with all
        improvements thereon, which consist of one building with 12,860 square
        feet of which approximately 6,300 is warehouse space and 2,800 is first
        floor office space, and 3,760 is second floor office space ("Demised
        Premises").

        1. TERM AND RENT. The term of this Lease shall be for the period
commencing on April 1, 2002 ("Commencement Date") and expiring March 31, 2004.
Notwithstanding the foregoing, Tenant shall pay to Landlord base rental, subject
to upward adjustment as set forth in Paragraph 2 below, in equal monthly
installments of $8,100 each month, plus sales taxes, on the first day of each
month in advance. Landlord does hereby acknowledge receipt of $8,100, plus
sales taxes of $567 representing the rental for April 1 through April 30, 2002.
Each monthly rent payment shall be payable at: 2034 Harvard Street, Sarasota,
Florida 34237.

        2. INCREASED RENTAL. Commencing on the date one (1) year after the
Commencement Date of this Lease ("Anniversary Date"), the rental hereunder shall
be increased by the percentage, if any, of increase in the Consumer Price Index
as of the Anniversary Date over that which existed on the commencement of the
first year of the term of this Lease. Such increase shall be determined by
Landlord who shall notify Tenant thereof. The increase shall be payable equally
with the regular rental payments. "Consumer Price Index" shall mean the Consumer
Price Index as now published by the U.S. Bureau of Labor Statistics under the
caption: "United States City Average for Urban Wage Earners and Clerical Workers
All Items", 1984 equals 100; or any revision or equivalent thereof hereafter
published by that Bureau, or if there ceases to be any such publication, any
substantially equivalent Price Index generally recognized as authoritative,
designated by Landlord.

        3. SECURITY DEPOSIT. Simultaneously with the execution of this Lease,
Tenant shall deliver to Landlord a security deposit in the amount of $8,100 (the
"Security Deposit"). The Security Deposit shall be Landlord's as security for
the faithful performance by Tenant of Tenant's covenants and obligations under
this Lease, it being expressly understood that such Security Deposit shall not
be considered an advance payment of rent or a measure of Landlord's damage in
case of a default by Tenant. The Security Deposit may be commingled with
Landlord's

<PAGE>

funds without accounting therefor to Tenant. Upon the occurrence of any event of
default by Tenant, Landlord may, from time to time, without prejudice to any
other remedy, use such security deposit to the extent necessary to make good any
arrearage of rent or other charges unpaid by Tenant and any other damages,
injury, expense or liability caused to Landlord by such event of default.
Following any such application of the Security Deposit, Tenant shall promptly
pay to Landlord on demand the amount so applied in order to restore the Security
Deposit to its original amount. If Tenant is not then in default hereunder, any
remaining balance of such Security Deposit shall be returned by Landlord to
Tenant upon termination of this Lease.

                In the event of sale or conveyance of the Demised Premises, such
sale or conveyance shall be subject to this Lease and Landlord shall pay over
the balance of such deposits and any advanced rent in its possession to the
purchaser and Landlord shall thereupon be relieved from all liability with
respect to same and Tenant shall look solely to the purchaser with respect
thereto. Tenant agrees that from time to time upon no less than ten (10) days
prior request by Landlord, Tenant will deliver a statement in writing certifying
all of the following:

           a. That the Lease is unmodified and in full force and effect (or, if
there have been modifications, that the Lease as modified is in full force and
effect and stating the modifications);

           b. The dates to which the rent and other charged have been paid;

           c. The annual rental rate then in effect;

           d. The Lease term;

           e. That all conditions to Tenant's possession of the Demised Premises
and commencement of the Lease term have been satisfied, if true; and

           f. That Landlord is not in default under any provisions of this
Lease, if true; and

           g. Any other information reasonably requested by Landlord.

              It is intended that any such statement delivered pursuant to this
Paragraph may be relied upon by any prospective purchaser or mortgagee of the
Demised Premises.

        4. QUIET ENJOYMENT. Provided Tenant shall pay all rents as herein agreed
and keep and perform all of the terms, covenants and conditions hereof, Tenant
shall peaceably possess and quietly enjoy the Demised Premises without hindrance
or interruption subject only to the terms hereof, reservations, restrictions and
easements of record and applicable zoning and other governmental regulations.

        5. USE OF PREMISES. Tenant shall use the Demised Premises solely for the
purpose of all actions, processes and services associated with developing,
testing, production, manufacturing, marketing and sales of the Tenant's presence
sensing products and Subtenant's sparkplug products, services and property and
related uses, and no other use shall be made thereof without the prior express
written consent of Landlord. Tenant shall make no immoral, offensive or illegal
use of the Demised Premises or do anything thereon deemed extra hazardous or
which would cause insurance rates to increase. Tenant shall abide by all
reasonable directions and requirements of any insurance company insuring the
Demised Premises and shall keep and




                                       2
<PAGE>

abide by all laws, ordinances, rules and regulations of all governmental bodies
and their respective regulatory agencies having any jurisdiction over the
Demised Premises. Tenant shall not commit or suffer any waste in or about the
Demised Premises.

        6. UTILITIES. Tenant shall be billed directly for and shall pay all
charges for all electricity to the Demised Premises and water and sewer for the
Demised Premises, including connection charges and deposits, if required. Tenant
shall be responsible for garbage and trash collection for the Demised Premises.
Tenant shall pay for all other utilities used or furnished to the Demised
Premises at the request of Tenant during the term hereof.

        7. TENANT'S MAINTENANCE. Tenant shall maintain and be responsible to
pay up to the first $500 in repairs and maintenance costs of items in the
interior of the Demised Premises, including interior ceilings, walls, floors,
plumbing, electrical and other fixtures, heating and air conditioning equipment,
pipes, doors, windows and glass, and overhead doors ("Interior Items"). In each
instance where a repair to or maintenance of an Interior Item is undertaken
which was caused by defect or ordinary wear and tear (and not caused by the
fault of the Tenant), the Landlord shall be responsible for the payment of all
amounts in excess of $500 in each such instance. Tenant shall make no material
alterations or structural changes to the improvements on the Demised Premises
without the prior written consent of Landlord, which shall not be unreasonably
withheld. Tenant shall also be billed directly for and pay the regular
maintenance fees charged by the Northgate Center Association (which are
presently $83.59 per calendar quarter) and covering the term of this Lease, as
it may be renewed. Landlord shall pay any special assessments levied on the
Demised Premises by the Northgate Center Association. Upon the commencement of
this Lease and the termination of this Lease, if it does not coincide with the
Association's billing cycle, Tenant shall pay to Landlord its pro rata amount of
the Association fees until the beginning of the next billing cycle, if at the
beginning of the Lease term, and from the end of the last billing cycle to the
date of termination, upon termination of the Lease.

        8. LANDLORD'S MAINTENANCE. In addition to Landlord's obligations under
Paragraph 7 above, Landlord, at Landlord's sole expense, shall: maintain the
exterior walls, roof, and foundation of the Demised Premises in good and
substantial repair; maintain all landscaping located on the Demised Premises in
a clean and sightly condition, and in good and substantial repair; and maintain
all pavement, parking areas and driveways of the Demised Premises in a clean and
sightly condition and in good and substantial repair.

        9. SIGNS. Tenant shall have the right to construct and place exterior
signs at the Demised Premises as it deems appropriate; provided any such sign or
signs comply with all rules, regulations, laws, statutes, ordinances and/or
governmental authorities, and the rules of the Northgate subdivision and
further, provided that any such sign or signs are erected and maintained so as
to not cause damage to the Demised Premises.

        10. LIABILITY INSURANCE AND INDEMNIFICATION. Tenant agrees to indemnify
the Landlord against any and all claims for personal injury or property damage
caused by any defects in the Demised Premises which defects result from Tenant's
failure to maintain the Demised Premises in accordance with the terms of this
Lease. Tenant further agrees to indemnify and hold Landlord harmless against
any and all claims for personal injury or property damage



                                       3
<PAGE>

arising from the use or occupancy of the Demised Premises by Tenant provided
such claims do not result from defects in the Demised Premises for which
landlord is responsible. In addition to the foregoing, Tenant shall carry and
pay for general liability insurance fully protecting and insuring Landlord and
Tenant from and against any liability, claim, loss, damage or expense arising
out of any of the foregoing with limits in an amount not less than $1,000,000
for injury to or death of any one person, $2,000,000 for injury to or death of
any number of people arising out of any one occurrence and $250,000 for damage
to property. Said liability insurance shall be carried in a solvent reputable
insurance company authorized to do business in the State of Florida and approved
by Landlord. Tenant shall furnish a certificate showing said insurance to be in
full force and effect prior to taking possession.

        11. TAXES. Landlord shall pay all ad valorem and real estate taxes and
assessments, regular or special, levied or assessed against the Demised
Premises. Tenant will pay any sales tax on the aforesaid rental payments and
will also pay all taxes and assessments now or hereafter levied against personal
property owned by Tenant and located within or upon the Demised Premises.

        12. FIRE AND CASUALTY INSURANCE. Landlord shall keep the improvements
situated on the Demised Premises insured against loss or damage by fire and
extended coverage insurance. Landlord shall pay the premium for such insurance.
If Tenant conducts any activity upon the Demised Premises which would cause the
premium for such insurance to be increased, Tenant will be responsible to pay
for the amount of increase.

        13. DESTRUCTION OF PREMISES. In the event of the total destruction of
the improvements on the Demised Premises or such substantial partial destruction
thereof by fire or otherwise as will cause the entire Demised Premises, in the
reasonable determination of the Tenant, to be unfit for the aforesaid use, this
Lease shall be terminated and the rights of all parties hereunder shall cease
except such rights and liabilities as may have accrued to the time of such
destruction. In the event of partial destruction of the Demised Premises by fire
or otherwise and said partial destruction, in the reasonable determination of
the Landlord, does not render the same unfit for the use aforesaid, the rent
shall abate for that portion of the Demised Premises rendered untenantable. Such
abatement in the rent shall continue only for such period of time as the portion
of the Demised Premises is rendered untenantable. In the event of such partial
destruction, Landlord shall restore the same within a reasonable period of time.

        14. WAIVER OF DEFAULT. No waiver of any breach of any of the terms,
covenants and conditions hereof shall be taken or construed to be the waiver of
any other or succeeding breach of the same or any other term, covenant or
condition hereof.

        15. CORRECTIONS OF DEFAULTS. If Tenant defaults in any of the terms,
covenants and conditions hereof, Landlord may perform the same or procure the
performance thereof without waiving or affecting the option to terminate the
term hereof or waiving said default or waiving any rights hereunder, and all
payment or payments or expenditures (including reasonable attorney's fees as
hereinafter provided) made by Landlord in so doing shall be charged to Tenant,
shall become immediately due and payable and shall bear interest at the rate of
18% per annum from the date of disbursement by Landlord until paid by Tenant.



                                       4
<PAGE>



        16. IDENTITY OF INTEREST. The execution of this Lease or the performance
of any of the terms hereof shall not be deemed or construed to have the effect
of creating, between Landlord and Tenant, the relationship of principal and
agent or of a partnership or of a joint venture and the relationship between the
parties hereto shall always be and remain that of Landlord and Tenant.

        17. DEFAULT. In the event Tenant shall be in default in the payment of
rent for more than three days (after notice of such default in writing, in
accordance with Florida Statutes) or if Tenant shall continue in default in the
observance or performance of any of the terms, covenants and conditions
hereof after 15 days notice of such default in writing (via certified mail),
Landlord, with legal process, may:

            a. Treat this Lease as terminated and resume possession of the
Demised Premises and remove all persons and property from the Demised Premises,
and store such property in a public warehouse or elsewhere at the cost of and
for the account of Tenant; or

            b. Retake possession of the Demised Premises for the account of
Tenant and relet the Demised Premises, or any part thereof, for such term or
terms and at such rental and upon such other terms and conditions as the
Landlord may deem advisable, in which event the rents received by the Landlord
from reletting shall be applied first to the payment of such expense as Landlord
may be put to in reentering, and then to the payment of the rent due and to
become due under this Lease, the balance, if any shall be paid over to Tenant,
who shall remain liable for any deficiency; or

            c. Stand by and do nothing and shall have the right to sue Tenant as
each installment of rent matures, or accelerate the balance of installments due
and sue on the same.

            No such reentry or taking possession of the Demised Premises by
Landlord shall be construed as an election on its part to terminate this Lease,
unless written notice of such intention be given to Tenant, or unless the
termination thereof be decreed by a court of competent jurisdiction.
Notwithstanding any such reletting without termination Landlord may, at any time
thereafter, elect to terminate this Lease for any breach, and in addition to any
other remedies it may have, it may recover from Tenant all damages that it may
incur by reason of such breach including the cost of recovering the Demised
Premises.

            Any remedy that Landlord may pursue, as described in Subsections a,
b, and c above, shall be subject to and taken in accordance with the applicable
requirements and provisions of Chapter 83 of the Florida Statutes.

            In the event Tenant defaults or breaches any of the terms,
conditions or promises of Tenant herein contained, and Landlord is put to the
necessity of employing an attorney in order to collect any sum or sums of money
which may be due by reason of such default, or otherwise take such steps or
legal action as may be necessary to enforce such terms, conditions or promises,
then Tenant agrees to pay a reasonable attorney's fee, paralegal, legal
assistant and similar fees and court costs and expenses in connection therewith
whether for negotiation, trial, appeal or bankruptcy representation.

        18. ADDITIONAL EVENTS OF DEFAULT. If Tenant shall make any assignment
for the benefit of creditors, file a petition in bankruptcy or be adjudged
bankrupt after filing of an involuntary petition, take or receive the advantage
or benefit of any insolvency or bankruptcy act,



                                       5
<PAGE>

enter into an agreement of composition with creditors, or if a receiver shall be
appointed to take control of the business of Tenant, same shall constitute a
default hereunder and Landlord may, at Landlord's option, by giving 15 days
written notice to Tenant, pursue Landlord's remedies set forth in Paragraph 17
above.

        19. ACCESS TO PREMISES BY LANDLORD. The Landlord or any of
Landlord's agents shall have access to the Demised Premises and all parts
thereof during normal business hours with at least 24 hours advance notice
(which may be telephone, facsimile, or in writing) for the purpose of examining
same and to make such repairs as Landlord deems advisable.

        20. NOTICES. Any notices or other communications required or permitted
hereunder shall be in writing and shall be sufficiently given if delivered
personally or sent by registered or certified mail, postage prepaid, addressed
as follows or to such other address of which the parties may have given notice:

<TABLE>
<S>                                                    <C>
If to Landlord:   DTS Commercial Interiors, Inc.        With copy to: SABA & KING
                  2034 Harvard Street                                 Attorneys at Law
                  Sarasota, Florida 34237                             2033 Main Street, Suite 303
                                                                      Sarasota, Florida 34237

If to Tenant:     Invisa, Inc.                          With copy to: Bill Dolan, Esquire
                  4420 Independence Court                             416 Burns Court
                  Sarasota, Florida 34234                             Sarasota, Florida 34236
</TABLE>

        21. CONDEMNATION. In the event that any portion of the Demised Premises
or all of the Demised Premises are taken under condemnation proceedings, or by
sale under threat of condemnation, Tenant shall have no right to any portion
of the condemnation award. This does not preclude the Tenant from the right to
recover for business damages and relocation expenses if any, to which it may be
entitled under applicable law. If the portion of the Demised Premises taken is
such that Tenant, in Tenant's determination, is not materially affected in the
conduct of Tenant's business, then this Lease shall continue in full force and
effect with no abatement of rentals to be paid hereunder as though such property
was not taken. If, on the other hand, the taking of a portion of the Demised
Premises is such as to, in the determination of Tenant, materially affect the
conduct of Tenant's business, then and in that event, Tenant shall have the
right to an equitable abatement of rent hereunder. If Landlord and Tenant cannot
agree on an equitable rental reduction, then the same shall be referred to a
panel of three (3) arbitrators, one of which is appointed by each party, and the
third appointed by the first two arbitrators, who shall meet within ten (10)
days of appointment and then and there determine a fair reduced rental, both
parties covenanting and agreeing to be bound by the arbitration decision. In the
event that the portion or amount of property taken by condemnation or by sale
under threat of condemnation is such as to preclude Tenant, in Tenant's
determination, from effectively conducting Tenant's business, then Tenant shall
have the right to cancel and terminate this Lease which said right shall be
exercised, if at all, by Tenant so notifying Landlord within fifteen (15) days
after the taking or conveyance of the property.


                                       6
<PAGE>



        22. SUBORDINATION. Tenant agrees that this Lease shall be subject and
subordinate to any mortgage now a lien upon the aforesaid Demised Premises or
any future mortgage executed by Landlord intended to become a mortgage lien
against the Demised Premises. Tenant further agrees that upon the request of
Landlord, it will promptly execute such documents as may be requested in order
to subordinate this Lease to the lien of any present or future mortgage,
irrespective of the time of execution or time of recording of any such mortgage
or mortgages, provided that the holder of any such mortgage shall enter into an
agreement with Tenant, in recordable form, that in the event of foreclosure or
other right asserted under the mortgage by the holder or any assignee thereof,
this Lease and the rights of Tenant hereunder shall continue in full force and
effect and shall not be terminated or disturbed except in accordance with the
provisions of this Lease. Tenant agrees that if requested by the holder of any
such mortgage it will be a party to said agreement and will agree in substance
that if the mortgagee or any assignee of said mortgage shall succeed to the
interest of Landlord in this Lease, it will recognize said mortgagee or assignee
as its Landlord under the terms of this Lease. Tenant agrees that it will, upon
request of Landlord, execute, acknowledge and deliver any and all instruments
necessary or desirable to give effect to or notice of such subordination. The
word "mortgage" as used herein includes mortgages, deeds of trust, or other
similar instruments and any modification, consolidation, extension, renewal,
replacement or substitution thereof.

        23. PARKING. Tenant shall not obstruct, or permit to be obstructed,
the driveway furnishing access to the Demised Premises.

        24. REMOVAL OF IMPROVEMENTS BY TENANT. Upon the termination of this
Lease, provided that Tenant is not then in default under the terms hereof,
Tenant may remove any and all manufacturing equipment, furniture and furnishings
which may have been furnished and installed by Tenant, provided that Tenant at
its expense repairs any damage resulting from such removal so as to restore the
damaged portion of the Demised Premises to the condition existing prior to the
installation and removal thereof. All other improvements made to the Demised
Premises by the Tenant and all fixtures of whatsoever kind and nature as shall
be fastened to the Demised Premises by the Tenant, not hereinabove specifically
enumerated, shall be deemed to become a part of the Demised Premises herein
described upon the termination of this Lease and shall not be removed by the
Tenant. Tenant further agrees that upon the termination of this Lease or any
extension hereof, either by the expiration of its term or otherwise, Tenant will
quit the possession thereof and leave the Demised Premises in good, usable
condition, equal at least to the same condition as existing at the commencement
of the term of this Lease, reasonable wear and tear excepted and "broom clean".

        25. CONSTRUCTION OF IMPROVEMENTS. Landlord shall make the following
repairs and improvements, on or before April 1, 2002, to the Demised Premises,
and shall be responsible to pay the contractor therefor:

            a. Repair damaged areas of the walls throughout the second floor
office areas.

            b. Paint the walls in the second floor office areas with the type of
paint and color to be selected by Tenant.




                                       7
<PAGE>



            c. Install new carpet throughout the second floor office space areas
of the type and color selected by Tenant and of reasonable grade for similar
offices.

            d. Put in "broom clean" condition.

        26. OPTION TO RENEW. Tenant shall have the option to renew this Lease
for an additional one-year period i.e., from April 1, 2004 to March 31, 2005
("Renewal Term"). The rent for the Renewal Term shall be increased by the
percentage, if any, of increase in the Consumers Price Index as of April 1, 2004
over that which existed on the commencement of the first year of the term of
this Lease, and in all other respects, the terms and conditions of this Lease
shall remain unchanged and shall be the terms and condition of this Lease during
the Renewal Term. If the Tenant is to exercise this option to renew, it must do
so by delivering written notice to the Landlord no later than 90 days prior to
the end of the term of this Lease.

        27. ASSIGNMENT AND SUBLETTING. Except as stated in Paragraph 31(h)
below, no provisions of this Lease may be assigned in whole or in part without
Landlord's prior written consent and such consent shall not be unreasonably
withheld; provided that Assignee demonstrates equal or greater financial
strength than Tenant and Tenant remains obligated under the terms of this Lease.
The Demised Premises or portions thereof may be sublet with prior written
consent of Landlord which shall not be unreasonably withheld, and Landlord
hereby grants Tenant permission to sublet a portion of the Demised Premises as
Tenant deems appropriate to FlashPoint International, Inc. for its use of the
sublet portion for developing, testing (including testing on an engine
dynamometer), production, manufacturing, marketing and sales of sparkplugs.

        28. PARAGRAPH TITLES. Paragraph titles used herein are solely for
convenience and are not to be used in interpreting particular provisions
hereof.

        29. MISCELLANEOUS PROVISIONS AND DEFINITIONS. All of the terms and
provisions hereof shall be binding upon and the benefits inure to the parties
hereto and their respective heirs, devisees, personal representatives,
successors and assigns. The term "Tenant" and "Landlord" shall include all
parties so designated herein, their respective heirs, devisees, personal
representatives, successors and assigns. Whenever used herein, the singular
number shall include the plural, the plural the singular and the use of any
gender shall include all genders. This Lease and all instruments or documents
relating to same and all references herein shall be construed under Florida law.
The venue of any action or suit brought in connection herewith shall be in the
Country wherein the Demised Premises are situate. Time is of the essence hereof.

        30. REQUIRED DISCLOSURE. Florida law requires the following
notification to be included in this Agreement:

            Radon is a naturally occurring radioactive gas that, when it is
            accumulated in a building in sufficient quantities, may present
            health risks to persons who are exposed to it over time. Levels of
            radon that exceed federal and slate guidelines have been found in
            buildings in Florida. Additional information regarding radon and
            radon testing may be obtained from your county public health unit.



                                       8
<PAGE>


        31. OPTION TO PURCHASE. For and in consideration of the sum of Ten
Dollars ($10.00) paid by Tenant to Landlord upon the execution hereof as
option money, Landlord does hereby grant to Tenant an option to buy upon the
hereinafter contained terms and conditions, as long as Tenant is not in default
hereunder, and for the period set forth in Paragraph a below, Landlord's land
and improvements located on Lots 16 and 17, Northgate Center Subdivision, Unit 4
Sarasota County, Florida.

            a. Exercise of Option. This option shall be exercised, if at all, by
notice in writing to Landlord, delivered to: 2034 Harvard Street, Sarasota,
Florida 34237, mailed postage prepaid and postmarked, or delivered personally to
Landlord before 12:00 Midnight, March 31, 2004. If not exercised within said
time, and in the manner required hereby, then this option shall thereupon
terminate and be of no further force or effect. In the event this option is
properly exercised, then Landlord agrees to sell and Tenant agrees to buy upon
the hereinafter contained terms and conditions the aforedescribed property.

            b. The purchase price of the property shall be $698,000.00, if
closed during the first year of the Lease Term. The purchase price of the
Property shall be $750,000 if closed during the second year of the Lease Term.

            c. Terms. The total purchase price shall be payable as follows:

               i. $10,000.00 by cashier's check which must accompany the
aforesaid exercise of the option for said exercise to be valid and effectual.

               ii. Balance in cash at closing, subject to prorations hereinafter
set forth.

            d. Closing. If there are no defects in title, closing shall be held
thirty (30) days after exercise of option at 10:00 o'clock, a.m. at the offices
of the Tenant's attorney in Sarasota County, Florida. At closing, upon receipt
of the aforesaid sums, Landlord shall execute and deliver to Tenant a sufficient
and recordable warranty deed conveying a good marketable record fee simple title
in and to the above described property subject only to zoning regulations and
taxes for the current year and easements, reservations and restrictions of
record. Landlord shall pay for required documentary stamps and surtax on said
deed. Possession shall be given to Tenant on the date of closing. Risk of loss
shall remain with Landlord until closing. Taxes shall be prorated as of the date
of closing.

            e. Defaults. If Landlord fails to perform any of the covenants
hereof, Tenant may, at Tenant's option, elect to have specific performance.
If Tenant fails to perform, Landlord may keep the $10,000 which accompanies the
exercise of the option as liquidated damages.

            f. Survey. Within ten (10) days from exercise of the option, Tenant,
at Tenant's expense, may obtain a survey of said property. If such survey shows
any violation of restrictions or governmental zoning regulations (including
Northgate Center Association's restrictions and regulations), or if any
improvements, are constructed over any easements, or if the improvements are not
entirely within the above described property, or if there are any encroachments
or overlaps, the same shall be deemed a defect in title.

            g. Title insurance. Within 10 days from exercise of the option,
Tenant shall, at Tenant's expense, obtain a title insurance binder written on
Attorney's Title Insurance Fund



                                       9
<PAGE>



agreeing to issue to Tenant, upon recording of the deed and other documents
required hereunder, an owner's title insurance policy in the full amount of the
purchase price. Said policy shall insure Tenant's title to the real estate
herein described without exception or qualification other than the standard
exceptions of such title insurance company and those matters set forth herein.
Tenant shall have ten (10) days from receipt of said binder to examine said
binder and shall notify Landlord within said time of any defect in title or
exceptions in said binder not herein agreed to by Tenant. Upon receipt of such
notice, Landlord shall have a reasonable period of time, not to exceed ninety
(90) days, to remove or correct same and shall use diligence in removing or
correcting same, including the bringing of lawsuits, and this sale shall be
closed within ten (10) days after receipt by Tenant of a title insurance binder
omitting the exceptions to which buyer has objected. If Landlord does not or
cannot correct such matters after a good faith diligent effort to do so, Tenant
may, at Tenant's option, elect to take title as is or terminate this Agreement
and Landlord shall refund the $10,000 option exercise payment.

            h. Assignment. Landlord acknowledges and agrees that Tenant may
assign his option to purchase to Tenant's subtenant, FlashPoint, Inc. If the
option is timely exercised, upon closing of the purchase, the remainder of the
Lease is terminated.

            i. Environmental Covenants, Representations and Warranties. The
provision of Paragraph 32 of the Lease are hereby made applicable to the terms
of this option to purchase and are hereby adapted to be environmental
covenants, representations and warranties of the Landlord as Seller and the
Tenant as Purchaser with respect to and as part of the sale of the Property
pursuant to this option to purchase, and shall survive the closing of the
purchase of the Property.

            j. Closing Costs. Landlord shall pay documentary stamps on the deed
and Landlord's Attorneys' fees. Tenant shall pay all other closing costs.

        32. ENVIRONMENTAL COVENANTS, REPRESENTATIONS AND WARRANTIES.

            a. Landlord represents to Tenant that to the best of its knowledge
and belief there are no underground petroleum storage tanks, pumps, or
associated piping upon or under the Demised Premises, nor is there Hazardous
Material (as hereinafter defined) upon or under the Demised Premises.

            b. Landlord represents to Tenant that to the best of its knowledge
and belief there is no currently existing claim or potential claim outstanding
with respect to the presence of any Hazardous Material (as hereinafter defined)
on or under the Demised Premises pursuant to any Environmental Law (as
hereinafter defined). Landlord shall not cause or permit any Hazardous Material
to be brought upon, kept or used in or about the Demised Premises by Landlord,
its agents, employees, contractors or invitees, without complying with the
requirements of all applicable federal, state and local laws, ordinances,
regulations or rules pertaining to the transportation, storage, use and disposal
of such Hazardous Material(s), including, but not limited to, obtaining all
necessary and proper permits required by such laws, ordinances, regulations, or
rules. If Landlord's representations and warranties set forth herein are untrue,
or if Landlord breaches the representations and warranties set forth herein or
the obligations stated in the preceding sentence or if contamination of the
Demised Premises by a Hazardous Material occurs



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<PAGE>



and such contamination is not the result of the action or omission of Tenant or
Tenant's employees, agents, invitees or independent contractors, the Landlord
shall indemnify, defend and hold Tenant harmless from any and all claims,
judgments, damages, penalties, fines, costs, liabilities or losses (including,
without limitation, sums paid in settlement of claims, attorneys' fees,
consultation fees and expert fees) which arise during or after the Lease term as
a result of such untruth, breaches or contamination. This indemnification of
Tenant by Landlord includes, without limitation, costs incurred in connection
with any investigation or site work required by any federal, state or local
government agency or political subdivision because of Hazardous Material present
in the soil or groundwater on or under the Demised Premises. The foregoing
indemnity shall survive the expiration or earlier termination of this Lease.

            c. Tenant shall not cause or permit any Hazardous Material to be
brought upon, kept or used in or about the Demises Premises by Tenant, its
agents, employees, contractors or invitees, without complying with the
requirements of all applicable federal, state and local laws, ordinances,
regulations or rules pertaining to the transportation, storage, sue and disposal
of such Hazardous Material(s), including, but not limited to, obtaining all
necessary and proper permits required by such laws, ordinances, regulations or
rules. If Tenant breaches the representations and warranties set forth herein or
the obligations stated in the preceding sentence or if contamination of the
Demised Premises by a Hazardous Material occurs and such contamination is not
the result of the action or omission of Landlord or Landlord's employees,
agents, invitees or independent contractors, the Tenant shall indemnify, defend
and hold Landlord harmless from any and all claims, judgments, damages,
penalties, fines, costs, liabilities or losses (including, without limitation,
sums paid in settlement of claims, attorneys' fees, consultation fees and expert
fees) which arise during or after the Lease term as a result of such untruth,
breaches or contamination. This indemnification of Landlord by Tenant includes,
without limitation, costs incurred in connection with any investigation or site
work required by any federal, state or local government agency or political
subdivision because of Hazardous Material present in the soil or groundwater on
or under the Demised Premises. The foregoing indemnity shall survive the
expiration or earlier termination of this Lease.

            d. As used in subparagraph (b) and (c):

               (i) The term "Environmental Law" means and includes without
limitation, any federal, state or local law, statute, regulation or ordinance
pertaining to health, industrial hygiene or the environmental conditions or,
under or about the Demised Premises, including, without limitation, each of the
following: the Comprehensive Environmental Response, Compensation and Liability
Act of 1980, as amended; the Resource Conservation and Recovery Act of 1976, as
amended; the Federal Hazardous Materials Transportation Act, as amended; the
Toxic Substances Control Act, as amended; the Clean Air Act, as amended; the
Federal Water Pollution Control Act, as amended; and the rules, regulations and
ordinances of the U.S. Environmental Protection Agency, the State of Florida and
the County of Sarasota and of all other agencies, boards, commissions and other
governmental bodies and officers having jurisdiction over the Demised Premises
or the property on which the Demised Premises are located or the use or
operation thereof, and

               (ii) The term "Hazardous Material" means and includes, without
limitation:




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<PAGE>



               (A) those substances included within the definitions of
"hazardous substances", "hazardous materials", "toxic substances", or "solid
waste", in any of the Environmental Laws.

               (B) those substances listed in the U.S. Department of
Transportation Table or amendments thereto (49 CFR 172 101) or by the U.S.
Environmental Protection Agency (or any successor agency) as hazardous
substances (40 CFR Part 302 and any amendments thereto);

               (C) those other substances, materials and wastes which are or
become regulated under any applicable federal, state or local law, regulation
or ordinance or by any federal, state or local governmental agency, board,
commission or other governmental body, or which are or become classified as
hazardous or toxic by any such law, regulation or ordinance, and

               (D) any material, waste or substance which is any of the
following: (1) asbestos, (2) polychlorinated biphenyls, (3) designated or
listed as a "hazardous substance" pursuant to Section 311 or Section 307 of
the Clean Water Act (33 U.S.C. Sections 1251 et seq.), (4) explosive, or (5)
radioactive.

        IN WITNESS WHEREOF the parties have hereunto set their hands and seals
the day and year first above written.


Signed, sealed and delivered
in the presence of:                         DTS Commercial Interiors, Inc.
                                            a Florida corporation


/s/                                         By: /s/
--------------------------------                --------------------------------
/s/
--------------------------------



                                             Invisa, Inc., a Nevada corporation

/s/                                          By: /s/
--------------------------------                 -------------------------------
/s/
--------------------------------




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