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#9 Double Window Security Envelopes, Flip and Seal, 500 Count

13 reviews

  • 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 
  • Flip 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


    In offices that send a high volume of business mail, making the process as quick and streamlined as possible is key. Eliminate the hassle of having to moisten standard gummed seals or removing the protective strips used in peel and seal envelopes; you need to go for the easiest closure of all, which you’ll find in flip and seal envelopes. No licking, peeling, or taping required; simply flip up the folded edge, then flip down the flap!

    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 can easily hold up to 10 sheets of standard letter size paper inside. 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, Flip and Seal, 500 Count

    Part #: BSS-92588-007

    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 flip and seal closure, 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 should be stored in a dry, clean environment, as the latex glue on the flap will deteriorate when exposed to dust or moisture. The glue will also break down over time, so for best results, expect the self-sealing glue to bear a standard shelf life of about 12 months from purchase.
    • 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-92588-007
    • SKU: RI-U0J3-ZQP0
    • Barcode: X001BXX521
    • Package dimensions: 12.1 x 9.4 x 4.3 inches
    • Package weight: 5 pounds
    Customer Reviews
    5.0 Based on 13 Reviews
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    Filter Reviews:
      Brittany L.
      United States United States
      Correct Size & Shipped Quickly

      The free 2 day shipping was perfect, the envelopes got here just as I was about to run out! We always stock this item because it fits Quickbooks invoices perfectly and seals tightly!

      RHONDA L.
      United States United States
      Love these envelopes!

      We are happy these envelopes don't come with a perforated flap anymore. We had trouble with those being torn open my the USPS mail machine and had several customers complain.

      Page C.
      United States United States
      Fast shipping & terrific envelopes

      They fit nicely in our desk drawers. We accidentally purchased a different type of flip and seal envelope last time, and they don't fit in our desk drawers. They continually get caught at the top. These envelopes are just perfect. And we couldn't believe how fast we received them.

      KEN L.
      United States United States
      Office envelopes

      Easy to order. Quick delivery. Used this style of envelope previously. They work great!

      Susan S.
      United States United States
      Great envelopes for QuickBooks invoices

      Envelopes fit QuickBooks invoices perfectly to show company name and logo and addressee. The security lining does its job well, as does the self-sealing fold-up flap. That is a very nice feature so no moistening is required to seal, nor will the flap stick to itself before use. The envelope also has the re-order number under the flap so I will know which ones to re-order when these are all used up. I highly recommend these for QuickBooks users.