E-commerce giant Amazon has taken significant steps into the bricks-and-mortar world in recent years, opening its own Go stores and acquiring Whole Foods.

The firm has been experimenting with payment options, including the use of “just walk out” technology, which taps sensors and cameras to track what items customers take from the shelves and then automatically charges through an app.

Now it has unveiled a new option, Amazon One, which uses “custom-built algorithms and hardware” to create and read a person’s unique palm signature. To sign up, users insert their credit card and then hover their palm over the device.

Initially, the system will be used at select Amazon Go stores, which have entry gates that customers currently get through by entering a code on their phone. Customers will take the goods they want and the card linked to their palm will be automatically charged.

However, Amazon plans to extend the rollout and also wants to sell to third parties, arguing it could be used for everyday activities like paying at a store, presenting a loyalty card, entering a location like a stadium, or badging into work.