No. 10 business envelopes feature double windows and a security tint to secure your documents. The top window measures 1" x 3" and is positioned 1/2" from the left side and 2-1/2" from the bottom, while the bottom window measures 1-1/8" x 4" and is located 1/2" from the left and 3/4" from the bottom. Designed with white wove material, side seam, and gummed seal, these envelopes are made from 24 lb paper for durability.