Quality Park, HCFS-1508 Window Envelopes, Redi-Seal, First Class, White, 100 per box,(54692) HCFA-1500-Compliant to work with Medicare Form HCFA-1500,Medicaid, and other health insurance forms SECURITY LINING: Security lined to protect any confidential information listed in the HCFA-1500 or other healthcare forms. FEATURES: 100, 4.5Wx1H window envelopes. 4.5WX1H: Windows assures your contents arrive at their correct location SECURE: Redi-Strip seak-adhesive closure will ensure your contents stay safe with the licking factor out of mind