Amazon Locker is a self-service package delivery service of parcel lockers offered by online retailer Amazon. Amazon customers can select any Locker location as their delivery address and retrieve their orders at that location by entering a unique pick-up code on the Locker touch screen. However, certain third-party sellers on Amazon may not be able to ship to an Amazon Locker, due to their use of other shipping services such as FedEx or UPS that require a signature. There are several sizes, but when ordering, amazon.com reports some parcels are too big to be delivered to a locker.