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#9 Single Window Security Envelopes, Gummed Seal, 500 Count

1 review

  • Durable and professional go-to standard 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 
  • Cost-saving gummed flap provides the strongest seal when moistened
  • Dark security tint lining keeps your important documents securely concealed throughout transit


The #9 security envelope is ideal for everyday business mailings, and we’ve designed our gummed seal no. 9 envelope to keep your documents safe and secure behind a strong permanent seal throughout transit.

This popular single window business envelope is made from a durable 24lb white wove paper and 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 smaller #8 return envelope as well – so you can make it simpler than ever for your clients to quickly return payments to you. And with our dark security tint lining the inside, your confidential mail will stay concealed and secure all the way to its destination.

It’s an envelope choice that’s simple enough for everyday letters and statements, yet professional and secure enough for even high-profile business communications.


#9 Single Window Security Envelopes, Gummed Seal, 500 Count

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 single 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 gummed envelope seal, which means it must be moistened in order to form a seal.
  • 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-92588-025
  • SKU: BSS-92588-025
  • Barcode: X001RWX1VL
  • Package dimensions: 12.1 x 9.4 x 4.3 inches
  • Package weight: 5.7 pounds
Customer Reviews
5.0 Based on 1 Reviews
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    Pamela R.
    United States United States
    Blue Summit #9 Single window envelopes

    We have been using your #9 Single Window Security Envelopes for several year & your order process is seamless & order arrived promptly