Use this First Class window envelope to easily mail any tax return or report. A blue interior tint adds security while the cellophane window allows the recipient’s name and address to clearly show through using a slip sheet. Add a professional touch by imprinting your return address on the back flap.Specifications:Size: 9 1/2″ x 11 1/2″Window Size: 1 5/8″ x 5 3/8″Window From Left Side: 1″Window From Bottom: 8 5/8”Weight: 28lbMaterial: White WoveFlap Opening: ShortSeal: Moisture