Amazon, the leading e-commerce retailer in the U.S., is testing its cashierless store concept in larger format spaces, according to The Wall Street Journal.

The report published late Sunday says that Amazon is testing the concept in a larger format store in Seattle, hoping the idea would work in larger sized stores with higher ceilings and more goods on the shelves.

The technology being used by Amazon allows customers to pick what they want from store shelves, but automatically charges them for the selections when they leave the store.

Amazon already has seven of the smaller format Amazon Go cashierless stores operating in Chicago, San Francisco and Seattle, which typically measure about 2,500 square feet, according to the report.