What’s an e-commerce giant supposed to do when it needs more warehouse space? If you’re Amazon, you just ask the merchants whose stuff you’re selling to share, by offering to let them slap Prime labels on their products.

See, Amazon wants to be able to offer a wider array of products to more people, and get those items to them as quickly as possible. So instead of building new warehouses, it’s taking the more cost-effective route of turning to its merchants.

The Seller Fulfilled Prime program now lets merchants sell things on Amazon as “Prime Eligible” even if Amazon doesn’t handle packaging and delivery, Amazon announced today (h/t Bloomberg). This way, merchants who able to meet “a high bar” for shipping speed and customer service can slap the Prime label on orders and ship them out themselves.

Previously, sellers could have their items shipped directly from Amazon and participate in the Prime program that way, but they then have to pay fees to store their items in Amazon’s warehouses, as well as for packing and picking orders.

Amazon said it’s boosted the inventory available for Prime delivery within two business days by six million items under its Seller Fulfilled Prime program.

“We’re dedicated to making the fulfillment technology that Amazon develops available to sellers,” said Peter Faricy, VP for Amazon Marketplace. “The FBA service and Seller Fulfilled Prime program are the greatest opportunities in e-commerce for sellers to easily reach loyal Prime members and expand their business. We are proud that we are empowering so many retailers to grow their business, many of them small businesses and entrepreneurs. In fact, 50% of the total units sold on Amazon are from sellers.”

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