Business Source Double Window Envelopes, No. 8-5/8", 3-5/8"x8-5/8", 500/BX, White (BSN42204) Box of 500No. 8 5 8 business envelopes feature double windows and a security tint to secure your documents. Design also features a white wove material, side seam and gummed seal. 24 lb. General Information Manufacturer: Business Source Manufacturer Part Number: 42204 Brand Name: Business Source Product Name: No. 8 5 8 Business Check Envelopes Marketing Information: No. 8 5 8 business envelopes feature double windows and a security tint to secure your documents.