1 Box. Coin Envelope, 28lb. Brown Kraft 3 1 / 8" x 5 1/2" Coin Envelopes. We offer a large selection of envelopes andß window envelopes in stock to match most of today's forms and checks. Browse our large selection of business envelopes including commercial, self seal, catalog, booklet, clasp, coin, tyvek, remittance, invitation and jumbos. Business image is important. Our quality business envelopes and letterhead will give your business a professional appearance in your daily communications..