what's the big news in priority mail flat rate boxes and envelopes from the postal service? over a billion used. with envelopes starting at just $4.90, flat rate shipping is the hassle-free way to ship. pass it on. with flat rate boxes, there's no need to weigh anything up to 70 pounds. if it fits, it ships. you ship all different sizes? distributor caps to brake shoes. so 4 box sizes come in handy. if it fits, it ships. documents to different states? coast to coast. with flat rate envelopes, i ship anywhere in the country international too, for a low flat rate. now, we'd like to pass on this offer to you. call or go online to order your free flat rate shipping kit. you get free boxes, envelopes and our helpful shipping guide. i'll even deliver them to your door for free. it's an offer too good to pass up. call or go online now to order your free priority mail flat rate shipping kit, only from the postal service.