Quality Park® #10 1/2 Healthcare Claim Form Envelopes are for CMS-1500 and other insurance forms. The reflex blue pattern protects sensitive information because it obscures the details of the contents, even when held up to light. These 24-lb white wove envelopes can be used for professional mailings; side seams provide a more modern, clean look. Address Window. Seam Type: Side; Flap Type: Commercial; Trade Size: #10 1/2; Security Tinted: Yes.