First class tax return mailers are software compatible to be used with Ultra Tax software packages. This envelope has a landscape orientation for the documents. Offset double windows simplify mailing by printing the cover sheet and having both the recipient address and return address show through the envelope windows. This envelope has a remoistening seal, as well as first class mail and diamond border imprinted on the envelope. Tax return envelopes measure 9-1/2" x 12" and open on the short side.