White window envelopes are available in three sizes. #10 which measures 9-1/2 x 4-1/8, #9 which measures 8-5/8 x 3-5/8 and 6-3/4 which measures 6-1/2 x 3-5/8. All three sizes have the same size window and window placement of 4-1/2 x 4-1/8 and are positioned 4-1/8 from the left side of the envelope and 1/2 from the bottom of the envelope. This window size and placement is standard in the industry. If you need a special window size and or placement, please give us a call. The window material is a clear poly and the paper is 24# bright white and the closure is a moistenable glue. These window envelopes are perfect for letters, invoices, statements, and checks. We offer quantities of 500 up to 10,000 on our website with higher quantities available for a quote. If you have any questions regarding our white window envelopes please give us a call or send us an email and we will be happy to answer your inquiries.