Number 9 Envelopes – The Perfect Fit for Business Reply Mail & Invoices

The Number 9 envelope (3 7/8" x 8 7/8") is a go-to choice for business reply mail, invoices, and standard document inserts. Designed to fit inside #10 envelopes, these envelopes are ideal for return mail, payment slips, and office correspondence. Whether you’re handling customer invoices, response forms, or business mailings, our high-quality Number 9 envelopes provide a secure, professional mailing solution.

Dimensions: 3-7/8" x 8-7/8", Max. Enclosure Size: 3-5/8" x 8-5/8"