EX-4.1



 Exhibit 4.1 
 




 
 ZQ|CERT#|COY|CLS|RGSTRY|ACCT#|TRANSTYPE|RUN#|TRANS# 
COMMON STOCK 
PAR VALUE $0.00001 
Certificate Number 
ZQ00000000 
aspen aerogels® 
COMMON STOCK 
THIS CERTIFICATE IS TRANSFERABLE IN CANTON, MA, JERSEY CITY, NJ AND COLLEGE STATION, TX 
Shares

**000000****************** 
***000000***************** 
****000000**************** 
*****000000*************** 
******000000************** 
ASPEN AEROGELS, INC. 
INCORPORATED UNDER THE LAWS OF THE STATE OF DELAWARE 
THIS CERTIFIES THAT 
** Mr. Alexander David Sample **** Mr. Alexander David Sample **** Mr. Alexander David Sample **** Mr. Alexander David Sample **** Mr. Alexander David
Sample 
**** Mr. Alexander David Sample **** Mr. Alexander David Sample **** Mr. Alexander David Sample **** Mr. Alexander David Sample ****
Mr. Alexander David 
Sample **** Mr. Alexander David Sample **** Mr. Alexander David Sample **** Mr. Alexander David Sample ****
Mr. Alexander David Sample **** Mr. Alexander 
David Sample **** Mr. Alexander David Sample **** Mr. Alexander David Sample ****
Mr. Alexander David Sample **** Mr. Alexander David Sample **** Mr. 
Alexander David Sample **** Mr. Alexander David Sample **** Mr. Alexander
David Sample **** Mr Alexander David Sample **** Mr. Alexander David Sample **** 
Mr. Alexander David Sample **** Mr. Alexander David Sample ****
Mr. Alexander David Sample **** Mr. Alexander David Sample **** Mr. Alexander David Sample 
**** Mr. Alexander David Sample ****
Mr. Alexander David Sample **** Mr. Alexander David Sample **** Mr. Alexander David Sample **** Mr. Alexander David 
Sample ****
Mr. Alexander David Sample **** Mr. Alexander David Sample **** Mr. Alexander David Sample **** Mr. Alexander David Sample **** Mr. Alexander

David Sample **** Mr. Alexander David Sample **** Mr. Alexander David Sample **** Mr. Alexander David Sample **** Mr. Alexander David Sample
**** Mr. 
Alexander David Sample **** Mr. Alexander David Sample **** Mr. Alexander David Sample **** Mr. Alexander David Sample ****
Mr. Alexander David Sample **** 
Mr. Alexander David Sample **** Mr. Alexander David Sample **** Mr. Alexander David Sample ****
Mr. Alexander David Sample **** Mr. Sample **** Mr. Sample 
MR. SAMPLE & MRS. SAMPLE & MR. SAMPLE & MRS. SAMPLE

CUSIP 04523Y 10 5 
SEE REVERSE FOR CERTAIN DEFINITIONS 
is the owner of

**000000**Shares****000000**Shares****000000**Shares****000000**Shares****000000**Shares****000000**Shares****000000**Shares****000000**Shares*** 
*000000**Shares****000000**Shares****000000**Shares****000000**Shares****000000**Shares****000000**Shares****000000**Shares****000000**Shares**** 
000000**Shares****000000**Shares****000000**Shares****000000**Shares****000000**Shares****000000**Shares****000000**Shares****000000**Shares****0 
00000**Shares****000000**Shares****000000**Shares****000000**Shares****000000**Shares****000000**Shares****000000**Shares****000000**Shares****00 
0000**Shares****000000**Shares****000000**Shares****000000**Shares****000000**Shares****000000**Shares****000000**Shares****000000**Shares****000 
000**Shares****000000**Shares****000000**Shares****000000**Shares****000000**Shares****000000**Shares****000000**Shares****000000**Shares****0000 
00**Shares****000000**Shares****000000**Shares****000000**Shares****000000**Shares****000000**Shares****000000**Shares****000000**Shares****00000 
0**Shares****000000**Shares****000000**Shares****000000**Shares****000000**Shares****000000**Shares****000000**Shares****000000**Shares****000000
**Shares****000000**Shares****000000**Shares****000000**Shares****000000**Shares****000000**Shares****000000**Shares****000000**Shares****000000*

*Shares****000000**Shares****000000**Shares****000000**Shares****000000**Shares****000000**Shares****000000**Shares****000000**Shares****000000** 
Shares****000000**Shares****000000**Shares****000000**Shares****000000**Shares****000000**Shares****000000**Shares****000000**Shares****000000**S 
***ZERO HUNDRED THOUSAND ZERO HUNDRED AND ZERO*** 
FULLY-PAID AND NON-ASSESSABLE SHARES OF
COMMON STOCK OF 
Aspen Aerogels, Inc. (hereinafter called the “Company”), transferable on the books of the Company in person or by duly authorized
attorney, upon surrender of this Certificate properly endorsed. This Certificate and the shares represented hereby, are issued and shall be held subject to all of the provisions of the Certificate of Incorporation, as amended, and the By-Laws, as
amended, of the Company (copies of which are on file with the Company and with the Transfer Agent), to all of which each holder, by acceptance hereof, assents. This Certificate is not valid unless countersigned and registered by the Transfer Agent
and Registrar. 
Witness the facsimile seal of the Company and the facsimile signatures of its duly authorized officers. 
President and Chief Executive Officer 
Vice President, Chief Financial Officer and Treasurer

ASPEN AEROGELS, INC. 
SEAL 2008 DELAWARE 
DATED DD-MMM-YYYY 
COUNTERSIGNED AND REGISTERED: 
COMPUTERSHARE TRUST COMPANY, N.A. 
TRANSFER AGENT AND REGISTRAR, 
By 
AUTHORIZED SIGNATURE 
1234567 







  

ASPEN AEROGELS, INC. 
 THE COMPANY WILL FURNISH WITHOUT CHARGE TO
EACH SHAREHOLDER WHO SO REQUESTS, A SUMMARY OF THE POWERS, DESIGNATIONS, PREFERENCES AND RELATIVE, PARTICIPATING, OPTIONAL OR OTHER SPECIAL RIGHTS OF EACH CLASS OF STOCK OF THE COMPANY AND THE QUALIFICATIONS, LIMITATIONS OR RESTRICTIONS OF SUCH
PREFERENCES AND RIGHTS, AND THE VARIATIONS IN RIGHTS, PREFERENCES AND LIMITATIONS DETERMINED FOR EACH SERIES, WHICH ARE FIXED BY THE CERTIFICATE OF INCORPORATION OF THE COMPANY, AS AMENDED, AND THE RESOLUTIONS OF THE BOARD OF DIRECTORS OF THE
COMPANY, AND THE AUTHORITY OF THE BOARD OF DIRECTORS TO DETERMINE VARIATIONS FOR FUTURE SERIES. SUCH REQUEST MAY BE MADE TO THE OFFICE OF THE SECRETARY OF THE COMPANY OR TO THE TRANSFER AGENT. THE BOARD OF DIRECTORS MAY REQUIRE THE OWNER OF A LOST
OR DESTROYED STOCK CERTIFICATE, OR HIS LEGAL REPRESENTATIVES, TO GIVE THE COMPANY A BOND TO INDEMNIFY IT AND ITS TRANSFER AGENTS AND REGISTRARS AGAINST ANY CLAIM THAT MAY BE MADE AGAINST THEM ON ACCOUNT OF THE ALLEGED LOSS OR DESTRUCTION OF ANY SUCH
CERTIFICATE. 
  

							
	The following abbreviations, when used in the inscription on the face of this
certificate, shall be construed as though they were written out in full according to applicable laws or regulations:
	 			 
	  TEN COM	 	- as tenants in common	 	UNIF GIFT MIN ACT	 	-
                                     Custodian
                                   
	 	 	 	
      (Cust)                      
                       (Minor)

	  TEN ENT	 	- as tenants by the entireties	 		 	under Uniform Gifts to Minors Act
                                   
	 	 	 	
                             
 (State)

	  JT TEN	 	- as joint tenants with right of   survivorship and not as tenants   in common	 	UNIF TRF MIN ACT	 	 -
                                     Custodian (until age
                  )

                (Cust)

	 	 	 	
              under Uniform Transfers to Minors Act
              

	 	 		 		 	
 (Minor)                        
                                         
  (State)

	 	 		 		 	 
	  Additional abbreviations may also be used though not in the above
list.

  

			
		 	PLEASE INSERT SOCIAL SECURITY OR OTHER IDENTIFYING NUMBER OF ASSIGNEE
	For value received,                                 
 hereby sell, assign and transfer unto	 	  

 


  
  

(PLEASE PRINT OR TYPEWRITE NAME AND ADDRESS, INCLUDING POSTAL ZIP CODE, OF ASSIGNEE) 
  

 
  

 

			
		
	  
 of the common stock represented by the within
Certificate, and do hereby irrevocably constitute and appoint
	  	Shares
		
	  
 to transfer the said stock on the books of the
within-named Company with full power of substitution in the premises.
	  	Attorney

  

													
	Dated: 	 	  
	 	20	 	  
	 		  	Signature(s) Guaranteed: Medallion Guarantee Stamp
	  
 Signature:
	 	  
  
	 	 	  	  

THE SIGNATURE(S) SHOULD BE GUARANTEED BY AN ELIGIBLE GUARANTOR INSTITUTION (Banks, Stockbrokers, Savings and Loan Associations and Credit Unions) WITH
MEMBERSHIP IN AN APPROVED SIGNATURE GUARANTEE MEDALLION PROGRAM, PURSUANT TO S.E.C. RULE 17Ad-15.

	  
 Signature:
	 	  
  
	 	  
		 	Notice: 	 	 The signature to this assignment must correspond with the name as written upon the face of the certificate, in every particular,
without alteration or enlargement, or any change whatever.
  
	 	  
		 		 		 		 		 		  	 

  

					
	



	  	The IRS requires that we report the cost basis of certain shares acquired after January 1, 2011. If your shares were covered by the legislation and you have sold or transferred the shares and requested a specific cost basis
calculation method, we have processed as requested. If you did not specify a cost basis calculation method, we have defaulted to the first in, first out (FIFO) method. Please visit our website or consult your tax advisor if you need additional
information about cost basis.	  	




	  	  
 If you do not keep in contact with us or do not have any activity in
your account for the time periods specified by state law, your property could become subject to state unclaimed property laws and transferred to the appropriate state.