9-1/2" x 12-1/2" ( 9.5" x 12.5" ), Neopost Machine Insertable Open End Catalog Envelope, No Window, Western Sulphite, White Sulphite Paper, SFI Certified, Vellum Finish, Center Seam, Flap Down, Remoistening Seal, 500 Qty / Box, 500 Qty / Ctn, 24.5 lbs. per Box