#9 Double Window Security Envelopes for Quickbooks Invoices, Self Seal, 500 Count


  • Durable and professional #9 business envelope for mailing invoices, statements, and other office mailing needs
  • Roomy enough for a return envelope to be included, so you can get paid faster
  • Low profile flap design creates a wide opening for easy and quick envelope stuffing 
  • Peel and seal flap is quick and easy to use without any need to lick or moisten the glue 
  • Dark security tint lining keeps your important documents securely concealed throughout transit


Frustrated by flip-and-seal envelopes sticking to other mail, or the yucky taste that comes with standard gummed seal envelopes? A peal-and-seal design is the answer, with no mess, no residual stickiness, and no need for moistening. A standard security envelope that’s ideal for everyday business use, our #9 mailer keeps your documents safe and secure behind the strong glue seal throughout transit and a dark security tint lining.

Made from a durable 24lb white wove paper, this envelope comes equipped with a low profile flap design, which makes it easy to fold and stuff up to 10 sheets of standard letter size paper inside with room for a #8 return envelope as well – so you can make it simpler than ever for your clients to quickly return payments to you.

It can also be used as a return envelope itself when sent inside a #10 envelope, making the #9 one of our most versatile envelope choices that’s simple enough for everyday letters and statements, yet professional and secure enough for even high-profile business communications.


#9 Double Window Security Envelopes for Quickbooks Invoices, Self Seal, 500 Count

Part #: BSS-92588-002

We stand behind our products completely. We understand that buying products online can sometimes be difficult because you cannot physically see what you are buying; however, if our product is not exactly what you are looking for or does not meet your expectations, then we welcome you to send them back anytime for a 100% refund. Click here for more information regarding refunds or returns >

Key Features:

  • #9 double window envelope
  • Dimensions: 8 7/8 inches X 3 7/8 inches
  • Security lining
  • 24lb white wove paper
  • Package quantity: 500 Count


  • This envelope is equipped with a self seal, which means it requires that you peel away the protective strip to reveal the glue. It does not require moistening, but cannot be used in a bulk mail machine. For envelopes that can be used in a mail machine, you’ll want to use a gummed seal envelope.
  • This envelope is not suitable for printing in a laser printer, as the heat will melt or warp the windows.
  • While this envelope will work with QuickBooks invoices, it is NOT suitable for sending QuickBooks checks, as check information will not line up properly in the windows. Please click here for envelopes suited for mailing QuickBooks checks.

Product Details:

  • Brand: Blue Summit Supplies
  • Part #: BSS-92588-002
  • Barcode: X001AZ4VOV
  • Package dimensions: 8.5 x 12 x 4.5 inches
  • Package weight: 5.6 pounds

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    Anna C.
    United States

    Great prices & free shipping

    I am a repeat customer because of price, quality and free shipping. The consistency in prices is also refreshing. Office supply stores are constantly changing the prices of items I order. With Blue Summit, the pricing is consistent, lower then the big stores and the free shipping is fast!