Business Source 04446 #7 Coin Envelopes, 3-1/2 x 6-1/2″, 28 lb. Brown Kraft, Box of 500. Coin envelopes are ideal for small parts, samples, seeds, enclosures, loose coins and payroll applications. Flaps feature deep gumming for a secure seal. No. 7 coin envelopes are made of sturdy, 28 lb. Kraft stock.