Cardholders can use the new Visa Micro Tag to pay for purchases under $25 by waving the device in front of a contactless payment terminal.

Visa says the device allows financial institutions to offer cardholders a companion device to an existing credit, debit or pre-paid account.

The tags can be easily manufactured and personalised as part of an automated manufacturing process similar to that of standard cards, says Visa. This helps issuers control costs while a new payment choice to customers.

"Consumers today are interested in using electronic forms of payment for small ticket purchases," says Pam Zuercher, vice president, product innovation and coordination, Visa USA. "As one of the smallest payment devices, the Visa Micro Tag allows cardholders to carry a payment device that delivers fast and convenient transactions, while also providing an added layer of security."

To mark the launch Visa is distributing fobs pre-loaded with $15 to the first 1000 San Francisco Giants fans entering the field club level at AT&T Park ahead of the game today.

"After using the Visa Micro Tag, consumers will understand how this innovative device can quickly make their lives easier by speeding them through checkout lines," says Zuercher.

However other card firms have already hit the market with contactless alternatives to cards, such as American Express which began pilots of its keyring-sized ccontactless payments device ExpressPay back in 2003. ExpressPay uses radio frequency identifier technology to transmit payment instructions to merchant terminals.

Keyfobs featuring Mastercard's contactless system, PayPass, are also available to Citibank cardholders.

Royal Bank of Canada's credit cardholders have been using Speedpass keyrings to pay for purchases at ExxonMobil petrol stations since 2001. The device transmits payment instructions to specially fitted terminals at ExxonMobil petrol stations in Canada. RBC rolled out the fobs to its debit cardholders last year.