Key chain

A key chain is probably the single most ubiquitous worn device. It is in some ways an ideal place to locate any small device one needs to carry:

• it is always carried when not at home (thus to any point of purchase)
• it often has tags or identifiers enabling its anonymous return to the user if it is dropped - key return services specialize in doing this, e.g. "War Amps" in Canada
• it is carried in a sturdy pocket suitable for bulky metal items

The Dexit system relies on a key chain device equivalent to a cash card - friendly retailers readers that take small amounts of money from the device.