Business Source Double Window Envelope, No. 10, 4-1/8"x9-1/2", 500/BX, White (BSN36694) Box of 500No. 10 business envelopes feature double windows and a security tint to secure your documents. Top window is 1" x 3" , 1 2" from the left side and 2 1 2" from the bottom. Bottom window is 1 1 8" x 4" , 1 2" from the left, and 3 4" from the bottom. Design also features a white wove material, side seam and gummed seal. 24 lb. General Information Manufacturer: Business Source Manufacturer Part Number: 36694 Brand Name: Business Source Product Name: No.