· Designed to meet first class mailing standards, our first class mail envelopes ensure solutions for mailing catalogs, magazines, projects, or multiple documents at once.· Crafted from durable 28lb. white wove paper, these first class mail envelopes deliver protection for professional and secure mailing· With a reliable, easy-to-use seal, you can trust that your contents remain secure throughout the mailing process without having to use glue· Our 9x12 first class mailing envelopes featuring a wide opening and a center seam design. This smart construction allows you to quickly stuff multiple pieces of business mail in our envelopes· Distinctive green first class markings ensure your envelopes are instantly recognized by mail carriers, guaranteeing prompt handling of your important mail.