Wallet Flap (envelope)
A style of envelope Flap - used on some commercials, order form envelopes, dual purpose, and collection envelopes. The Wallet Flap gives extra space for printing . Also see: Bankers Flap, Extension Flap, Hub Flap, Pointed Flap, Round Flap, Square Flap, and Standard Flap.
Bottom And Side Flaps, Seal Flap Shapes, Open End, Open Side
Image courtesy of International Paper