Adams 3 Up 1099 Envelopes are the perfect fit for your 3-per-page 1099 NEC and 1098 forms. Self sealing envelopes don't require moisture so you save time and reduce the mess of bulk mailings. Just peel and seal. These double-window envelopes have a complex security tint to obscure the appearance of letters and numbers. Keeps social security numbers and private data hidden, even when held to light. Precisely sized and aligned double windows ensure personal data is always out of view. Our 1099 tax envelopes fit 1099 NEC and other 3 up forms. Store self-seal 1099 envelopes in a cool, dry place for enduring quality. 3-3/4" x 8-3/4". 24 Per pack.