The CR2032 battery (no longer the less common CR3032) claims to last over a year with normal use, but if a Noke does run out of juice, you can simply tap a new battery onto the bottom contact points -- a newly added feature since the Kickstarter campaign -- for about three seconds, in order to give it enough power to unlock. After which, you can replace the battery inside. But what if your phone runs out of battery or is out of range? This is where the "Quick-Click code" comes in: Just tap in your pre-defined pattern of long and short pulses, and the Noke will unlock itself.

Fuz Designs is now taking pre-orders ahead of a February 2015 delivery. It's $59.99 each or $54.99 each if you buy two.

Edgar Alvarez contributed to this report.