Amazon.com's New Secret Weapon: Lockers - Yahoo Amazon's locker program works fairly simply. Customers who ship their item to a locker—typically in 7-Elevens, grocery or chain drugstores—are emailed a code after a package arrives that unlocks the door holding their merchandise. The lockers can hold only smaller items that weigh less than 10 pounds, such as books, DVDs or electronic devices like iPads. Users have several days to retrieve their merchandise. Users don't pay extra to use the service but the locker program helps Amazon save on certain shipping costs. ShopRunner's Ms. Dias said UPS and FedEx Corp. charge retailers as much as 20% more to deliver packages to residential addresses because it is more efficient to deliver multiple packages to a business address. Failed deliveries are expensive for online retailers because those consumers are more likely to call customer service, switch to a competitor, or get a replacement item.