It’s one of the most under-publicized policies of some of the biggest U.S. retailers: sometimes they give customers full refunds and let them keep unwanted items too.

Returnless refunds are a tool that more retailers are using to keep online shoppers happy and to reduce shipping fees, processing time and other ballooning costs from returned products.

Companies such as Amazon, Walmart and Target have decided some items are not worth the cost or hassle of getting back. Think a $20 T-shirt that might cost $30 in shipping and handling to recover. There are also single-use items, such as a package of plastic straws, that might be difficult to resell or medicines that could be unsafe to market again.

Analysts say the companies offering returnless refunds do it somewhat sporadically, typically reserving the option for low-cost objects or ones with limited resale value. But some online shoppers said they’ve also been allowed to keep more pricey products.

Dalya Harel, 48, received a return-free refund recently after ordering a desk from Amazon that cost roughly $300. When the desk arrived, she noticed it was missing some key pieces and would be impossible to put together, Harel said. She couldn’t request a replacement and have it within a reasonable time for the office of her New York lice detection removal service because the item was out of stock.

Harel, who routinely buys towels and other products from Amazon for her business, said her team reached out to the company’s customer service line. She was pleasantly surprised to hear she would get a refund without having to send back the desk.

“That’s one less headache to deal with,” Harel said. “It was really nice for us to not have to make an extra trip up to the post office.”

She used the desk pieces to create makeshift shelves in her office in Brooklyn.

A mysterious process

While the retail practice of letting customers keep merchandise and get their money back is not exactly a trade secret, the way it works is shrouded in mystery. Companies are not keen to publicize the circumstances in which they issue returnless refunds due to concerns over the potential for return fraud.

Even if brands don’t provide details about such policies on their websites, returnless refunds are expanding in at least some retail corners.

Amazon, which industry experts say has engaged in the practice for years, announced in August that it would extend the option to the third-party sellers who drive most of the sales on the e-commerce giant’s platform. Under the program, sellers who use the company’s fulfillment services in the U.S. could choose to offer customers a traditional refund for purchases under $75 along with no obligation to return what they ordered.

Amazon did not immediately respond to questions about how the program works. But publicly, it has pitched returnless refunds more directly to international sellers and those who offer cheaper goods. Items sold in an upcoming section of Amazon’s website, which will allow U.S. shoppers to buy low-cost goods shipped directly from China, will also be eligible for returnless refunds, according to documents seen by The Associated Press.

In January, Walmart gave a similar option to merchants who sell products on its growing online marketplace, leaving it up to sellers to set price limits and determine if or how they want to participate.