4-1/4" x 6-1/2" ( 4.25" x 6.5" ), Open Side Dual Purpose Mailer Envelope, No Window, Western Sulphite, White Sulphite Paper, SFI Certified, Vellum Finish, Side Seam, Flap Extended, Remoistening Seal, 500 Qty / Box, 4000 Qty / Ctn, 6 lbs. per Box