Parcel Select Ground is a USPS mail class that offers ground delivery service at very low rates for large or heavy packages. When using this mail class, shipments can weigh up to 70lbs. and delivery ranges from 2–8 days. Rates are based on distance, weight and mailpiece dimensions.
可以用自己的纸箱吗
这个服务我不熟悉。我一般用priority mail, 是邮局提供的盒子