Starbucks Japan is introducing rental cups on a trial basis to some stores in a bid to reduce waste. The company will begin the test next Monday at 10 stores in central Tokyo. The rental cups are made of stainless steel and can be used for any drink.

Customers can register for the service on their smartphones. They must return the cups within three days of their order. The service will be free of charge for the time being.

“The first step is to offer our customers an easy way to borrow and return cups,” said Fukawa Rei, a manager at Starbucks Coffee Japan.

“We’ll see how much the cups are used and then decide whether to expand the service.”

Starbucks says it will run the test until next May, then study how effective it was in reducing waste.