Citigroup Inc. is testing new technology that would allow customers to withdraw money with an eyeball scan or a code on a smartphone instead of a card swipe.

Citigroup is working with Diebold on the technology in Irving ATMs, which are significantly smaller than traditional ATMs, reported the Chicago Tribune. Diebold suggests the Irving terminal is more secure than traditional ATMs. It lacks a card reader, which thieves can "skim" for credit card data; it doesn’t require PIN entry, which simplifies the withdrawal process; and it doesn’t display transaction information on a screen, which could be monitored by others, the Tribune reported. It can complete cash withdrawals in less than 10 seconds.

Irving is not the first cardless ATM, the Tribune said. Rosemont, IL-based Wintrust Financial introduced dozens of such machines in early 2015. Chicago-based BMO Harris announced in March it would do the same.

Mass rollout may be years away, reported MarketWatch. Other big banks including J.P. Morgan Chase & Co. and Bank of America Corp., recently started internally testing their own cardless ATM technologies.

Interest from some of the largest U.S. banks signals that more consumers may see the option, reported the Wall Street Journal. “Larger players sometimes like to wait on the sidelines a little longer to see if a product has merit before investing in it,” said Daniel Van Dyke, an analyst at Javelin Strategy & Research.

“Everyone is doing more and more on their mobile device,” said Wayne Malone, Citigroup’s head of global ATMs, in an interview with the Journal. Between 2013 and 2015, the share of bank customers who said their first preference for basic banking was using their mobile phone rose to 13% from 5%, according to Javelin.

Proponents say the new technologies may give banks a weapon in the fight against frauds that target ATM transactions. Credit-scoring and analytics firm FICO said that the number of attacks on consumers’ debit cards used at ATMs in roughly the first three months of the year hit the highest level in at least 20 years, said the Journal