9" x 12" 3 Mil Poly Mailers Self Seal Shipping Mailing Envelopes Bags White Pack of 4000 Lip Size: 1.5 +/- . 3-millimeter thickness (+/- 5%). Usable Dimensions: 9 x 12. Paper Liner: Clear with antistat. Adhesive: Synthetic rubber  Hotmelt,  minimum +/- 1/8.