4-1/2" x 9-1/2" ( 4.5" x 9.5" ), Health Insurance Claim Poly Window Envelope, 1-1/8" x 4-3/4" Window, 3-7/8" From Left, 1-1/2" From Bottom, Western Sulphite, White Sulphite Paper, SFI Certified, Vellum Finish, Side Seam, Flap Extended, Pres-Stik, Blue Wesco Tint, 500 Qty / Box, 2000 Qty / Ctn, 7 lbs. per Box, These envelopes are designed for standard CMS Health Insurance Claim Forms (formerly HCFA).