When confidentiality is a must, Office Depot medical claim envelopes can help. Tinted for security, these #10 envelopes are specifically designed to accommodate your patients' medical claim forms. Right window envelopes for use with HCFA 1500 Medicare Claim Forms. Security-tinted inside for privacy and confidentiality. Made of 24-lb white wove, Office Depot medical claim white business envelopes (#10) offer a substantial feel. Box of 500 envelopes.