The shipping materials offered by Packagezoom are a minefield of issues. Their boxes are about as strong as a deck of playing cards, in contrast to the lightweight envelopes and mailers that they utilize, which act like sails and catch every breeze. It's like attempting to stop a leaking yacht with a piece of tissue paper if their packaging tape is any indication. Don't even get me started. Make sure that your shipments don't end up in a shipwreck. Stay away from the shipping supplies sold by Packagezoom.