Promise safe delivery these security envelopes. Sized for everyday documents but secured to protect confidential information, these envelopes take the commercial standard to a new level. Set up invoices, statements and personal records to align with the single window when placed inside. Fasten it with Reveal-N-Seal adhesive for a seal that both you and the recipient can depend on. Envelope/Mailer Type: Business/Trade; Envelope Size: 3 5/8 x 8 5/8; Closure: Self-Adhesive; Trade Size: #8 5/8.