Sure, there are plenty of travel-sized iPhone docks on the market, but how many of them can actually fit into your pocket? Of those, how many would slide snugly into your wallet?
The Card Speaker will surprise you. The ultra-thin piece of electronic equipment boasts the same dimensions as a standard credit card, complete with round beveled corners. It's only marginally thicker than your debit card or Mastercard and houses some impressive cutting-edge technologies. Its fineness is made possible by a thin film battery and a flexible loudspeaker. It even folds out to provide its own stand.
Take Jeabyun Yeon's Card Speaker out on-the-go and connect it to your smartphone anytime you want to pump up the volume.
The Same Size as a VISA, the Card Speaker is the Ultimate in Portability
Amelia Roblin — February 9, 2013 — Art & Design
References: behance.net & tuvie