Business Source Double Window Invoice Envelopes White is Perfect for sending checks invoices statements and more. No. 9 envelopes feature security tint and double windows and are compatible with most standard letter-size computer-generated invoices and statements. The 1-3/16 x 3-1/2 top window is positioned 3/8 from left and 2 from the bottom of the envelope. The bottom window (1 x 4 ) is 3/8 from the bottom. 24 lb. • Security tint keeps information hidden from view for added privacy. • Transparent windows allow convenient use with printed labels. • Gummed flap creates secure seal to prevent peeling during delivery. • Perfect for sending checks invoices statements and more. • Material: Wove. • Sold as 500/Box.