Review on Damsakya SHIPPING Corrugated Cardboard: Inch by Inch by Christopher Clearfield

These are your standard square shipping boxes. You need to seal the top and bottom with tape. The cardboard is thick, but not so stiff that packaging material could be dispensed with if the cardboard is not filled. They are not waterproof as they are made of cardboard, but they are no different from the standard bags. I had no problems with shipping via USPS. No additional postage is required for the size. Thermal labels stick easily to cardboard.