Customer Reviews for Staples InstantSeal Security Tinted #9 Double Window Envelopes, 3 7/8" x 8 7/8", White, 500/Box (ST63338)
Item # : 1775861
Model # : ST63338
Send mail easily with this 500-pack of Staples InstantSeal security-tinted double-window self-sealing #9 envelopes.
- New and improved envelope
- Tamper proof, perforated seal to keep documents safe
Price is $39.99
Unit of measure 500/Box Price per unit $0.08/Envelope
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17 reviews
Most helpful positive review
Posted Nov 2, 2025
Well made and secure envelopes
When sending confidential documents and/or checks in the mail, these are a great envelope option. The envelopes have the security print on the inside to obscure the view, if held to the light. They also have good sized address windows located on the front.
When handling the envelopes, it's apparent that they are made with quality and convenience in mind. The paper used...
When handling the envelopes, it's apparent that they are made with quality and convenience in mind. The paper used...
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BreSweeney88
This reviewer received a free product or coupon in exchange for an unbiased review of the product
Posted Nov 2, 2025
Well made and secure envelopes
When sending confidential documents and/or checks in the mail, these are a great envelope option. The envelopes have the security print on the inside to obscure the view, if held to the light. They also have good sized address windows located on the front.
When handling the envelopes, it's apparent that they are made with quality and convenience in mind. The paper used...
When handling the envelopes, it's apparent that they are made with quality and convenience in mind. The paper used...
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Brahm337
This reviewer received a free product or coupon in exchange for an unbiased review of the product
Posted Nov 1, 2025
Lots of envelopes in the box but instant seal bad
The staples double window envelopes with instant seal has 500 envelopes in a box! It’s a great deal! The size is perfect for letters or anything else you want to fit in it and the double window makes it great to send letters out easily without having to write out the address. The only thing I had an issue with was the instant seal. For many of the envelopes, it didn’t c...
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Leelah
This reviewer received a free product or coupon in exchange for an unbiased review of the product
Posted Nov 1, 2025
Perfect
These #9 envelopes are excellent quality. The box includes a generous quantity, and the self-adhesive seal is very convenient—no need to lick or apply glue. The adhesive is strong and secure, ensuring the envelopes stay sealed once closed. I also appreciate that they’re not see-through and feature a double window, which makes mailing statements quick and efficient. Over...
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BrooklynDad
This reviewer received a free product or coupon in exchange for an unbiased review of the product
Posted Oct 31, 2025
Great Quality Envelopes Perfect Size
I was really impressed with these #9 white envelopes! The quality is excellent — the paper feels sturdy and professional, not thin or flimsy like some cheaper options. The size (3.875 x 8.875) is perfect for standard letters, invoices, or business correspondence, and they fit perfectly into mailing envelopes or folders without extra bulk.
The quantity was great for the...
The quantity was great for the...
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Past
This reviewer received a free product or coupon in exchange for an unbiased review of the product
Posted Oct 31, 2025
Great self adhesive envelopes
I think these are great windows self adhesive envelopes. The look and function of the envelope is great. The only hang up I had were a few had overly sticky adhesive so when attempting to unstick to seal the envelope the flap ripped
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Jenn0830
This reviewer received a free product or coupon in exchange for an unbiased review of the product
Posted Oct 31, 2025
Outstanding quality all around
I absolutely love the #9 3.875 x 8.875 white envelopes. They couldn't be more perfect for my business. For starters, they have a nice professional look and feel to them. My favorite feature and what sets these envelopes apart from the rest, is the seal quality. They offer an instant seal by simply lifting the flap and closing the envelope. The seal is the strongest I've...
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MomAlli
This reviewer received a free product or coupon in exchange for an unbiased review of the product
Posted Oct 31, 2025
Quality envelope
These are nice envelopes. I love the adhesive instant seal, it makes sending mail a breeze. The size is your standard size with a nice window making it easy for business to display the address. The pack of 500 envelopes means we will never run out. I appreciate the small slice, which I imagine is to help to rip open the envelope.
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LeoB
This reviewer received a free product or coupon in exchange for an unbiased review of the product
Posted Oct 31, 2025
great envelopes
I was sent a box of 500 white security peel and stick envelopes )#9 3.875 X 8.875). They are a perfect addition to my office supplies. I frequently do mailings and love that I don’t have to worry about the security print being transparent. Additionally I’m thankful that the adhesive seal actually stays sealed. I have purchased bulk envelopes in the past where the adhesi...
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Swimdozer
This reviewer received a free product or coupon in exchange for an unbiased review of the product
Posted Oct 31, 2025
Great self sealing envelopes
We help our neighborhood pool send out membership information every year but have never sprung for the self sealing option. Using a few of these the past couple weeks had changed that, it is a game changer. The seal is strong and the envelopes themselves are well made.
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AvaP
This reviewer received a free product or coupon in exchange for an unbiased review of the product
Posted Oct 31, 2025
Great envelopes
These envelopes work perfectly for sending out invoices. The windows line up just right and the adhesive strip not only saves you from having to lick the seal but it saves time too! Would definitely recommend.
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JenniferK
This reviewer received a free product or coupon in exchange for an unbiased review of the product
Posted Oct 31, 2025
Nice envelope that does not improve on others
The envelopes are sturdy with nice thickness and feel However I find the closure confusing and sloppy
The back of the envelopes have a perforated strip of paper on the back that lifts to reveal glue However it’s unclear if you’re supposed to just lift the flap and seal it or tear it off. In either case, on every envelope I have tried the envelope has partially torn nea...
The back of the envelopes have a perforated strip of paper on the back that lifts to reveal glue However it’s unclear if you’re supposed to just lift the flap and seal it or tear it off. In either case, on every envelope I have tried the envelope has partially torn nea...
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jula1411
This reviewer received a free product or coupon in exchange for an unbiased review of the product
Posted Oct 31, 2025
Envelopes
These envelopes did exactly what they were supposed to do! They are great quality envelopes! The paper is sturdy, the adhesive seals well, and they arrived quickly. Perfect for my needs. The envelopes are well-made, reliable, and exactly as described. I received a large box, which is great, it will last a while.
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unwraplife
This reviewer received a free product or coupon in exchange for an unbiased review of the product
Posted Oct 31, 2025
Perfect for office use
I use these #9 3.875 X 8.875 White Envelopes for my home business. The paper is sturdy and durable to make it through the (sometimes aggressive!) USPS process. The address window is conveniently located and large enough that I don't have to be exactly precise in my folding!. The envelopes are easy to seal and stay sealed.
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K.T.
This reviewer received a free product or coupon in exchange for an unbiased review of the product
Posted Oct 15, 2025
Easy to Use
The envelopes came in a large quantity which is nice to have for a length of time with out needing more. In quality they are a standard envelope with typical thickness that does the job. Overall I like that it has the windows for the return and send to which makes ease of use worth having them. I also appreciated that they are self stick although one did rip when trying...
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E.H.
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Posted Oct 14, 2025
Excellent Envelopes for Business or Personal
5/5 stars for these envelopes. They are great for business or personal mailing with easy to use flap. No issues with sticking tabs whatsoever. Overall would purchase again.
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