No. 8-5/8 Double Window Envelopes are made of 24 lb. stock and include layered privacy features to keep checks secure. Reveal-N-Seal flap is perforated to show evidence of tampering. Security tint with pattern makes it difficult to read the contents even when held up to light. 3-5/8" x 8-5/8" envelopes feature double windows that fit QuickBooks or other payroll and accounts payable checks. Patented, fold-in-place closure won't seal prematurely. Just raise the bottom flap and press to seal.