No. 9 Double Window Envelopes display both sender and receiver addresses to mail statements and invoices. Reveal-N-Seal envelopes feature a perforated, tamper-evident, self-seal closure that clearly shows if someone has attempted to open the envelopes. Reflex blue pattern protects sensitive client information by obscuring the details of the contents even when held up to light. 24 lb. white wove envelopes feature side seams for a clean, professional look. 3-7/8" x 8-7/8" envelopes include a top window that measures 1-3/16" x 3-1/2" and positioned 3/8" from the left and 2" from the bottom. Bottom window measures 1" x 4" and is 3/8" from the left and 1/2" from the bottom.