This 500-pack of #8 double window security envelopes is designed specifically for QuickBooks and computer-printed checks. The strong self-seal closure and premium security tint ensure privacy and convenience for professional mailings. Features: 500 envelopes per box Size: 3 5/8 x 8 11/16 inches Double window layout – perfectly aligned for QuickBooks checks Self-seal flap – no moisture required Security-tinted interior for confidentiality Compatible with most laser and inkjet printed checks Not for invoices or non-check formats Ideal for accountants, small businesses, and payroll offices handling frequent check runs.