HCFA Self-Seal Window Envelopes for Claim Forms (No. 10-1/2) 4-1/2" x 9-1/2", White with Inside Security Tint - 250 ENVELOPES CMS 1500 - HCFA Self-Seal Window Envelopes for Claim Forms Size: No. 10-1/2, 4.5 x 9.5 inches White with Inside Security Tint Press and Stick, Easy to Seal Package of 250 Envelopes