This package contains 150 self-seal cardboard mailing envelopes hard, size 6.5 x 4.5 inches (16.51 x 11.43 cm), each labeled with 150 "DO NOT BEND" to protect your important items. Designed for convenience, they come with an easy peel-and-seal hard envelopes featuring strong adhesive, so no glue or water is needed, along with a tear strip for effortless opening. Made from durable 400gsm paperboard, these baseball card mailing envelopes provide sturdy protection for art prints, photos, CDs, certificates, documents, manuals, catalogues, booklets, invitations. Also this cardboard envelopes photography mailers ideal for post offices, logistic shipping companies, packaging wholesalers, mail order businesses, office stationery suppliers, online stores, and personal use, they offer a reliable solution for mailing flat and delicate materials.