The #10 Security Envelopes by Columbian come in a box of 500 with a rectangular shape and a size of 4-1/8 x 9-1/2 inches. These white envelopes feature a self-seal closure for convenience and security. Made of paper, they are designed for business and industrial use in packing and shipping applications. The item model number is COLO151, and the product dimensions are 9.5 x 4.13 x 0.04 inches, with an item weight of 6.34 pounds.