Amazon One, the technology that lets customers pay in shops by scanning their palm, is expanding to more stores in the greater Seattle area. The company says it’s available starting today in its 4-star store in Lynnwood, and in the coming weeks, Amazon One is also coming to its Amazon Books store in Bellevue and its 4-star and Pop Up stores in South Lake Union. In total, 12 of Amazon’s physical stores will soon feature the technology.

The e-commerce giant announced its palm recognition Amazon One system last year. It works by scanning your hand and identifying its unique characteristics like surface area details and vein patterns. Palm scanning technology has been around for a few years, and it’s pretty secure as biometric security methods go, though there are concerns about how Amazon might use the data gathered as part of the system.

So far, Amazon has made Amazon One available as a payment option across a number of its own-branded physical stores around Seattle. But in the longer term, the company hopes the convenience factor of being able to confirm your identity using just your hand will convince third-party businesses to use the service, too; the Amazon One website invites other companies to contact its sales team. That might include other stores or even locations like offices where the system could replace the need for NFC ID tags.