That's not all the TrackR does. Its press-to-find system lets you activate an audio alert, so you can find items that have slid down between cushions. A "cold and hot" indicator tells you how physically close you are to the device.
So how does it work in the real world? Keeping in mind that I only had a chance to test a prototype, pretty well.
The final unit will be quite flat, about 3.8 mm thick. The design is based around two CR2016 batteries, the CR2032's flatter little brother. You can pick these up for a buck or so apiece at the corner grocery or grab a five-pack with free shipping at DealExtreme for about $1.50. It feels like a slightly thicker credit card and is quite light.
The developer says the two batteries should offer up to a three-year battery life (their marketing materials, however, only promise 18 months) due to BLE's low-duty cycle. You should be able to (as he put it, riffing on Ron Popeil), "set it and forget it." The company has tested the power draw off the prototypes to come to this conclusion.
In use, I found the audio alert to be adequate. It's fairly tinny and high-pitched, so it was a bit hard to track down under normal family conditions -- with the TV on and kids yelling, but once they were hushed, I did quite well finding it in all the places my kids had hidden it. I paid them to play hide and seek with the test unit, to see how well the audio signal worked.
We found that it was quite easy to degrade the signal a bit by putting the unit in the pantry behind a closed door, shoving it under couch cushions, and so forth -- but that for a normal home, the alert worked well enough for the device to be found.
I also tested the "abandoned object" functionality, which provides the device leashing. Once I moved far enough away from the dongle, my phone vibrated and sounded, letting me know I had forgotten to take the dongle with me. This worked, as promised, even when I had other apps open -- such as Mobile Safari and Mail.
Aside from a few minor early prototype bugs, I also noticed that the software did drain my iPhone 4S battery slightly faster usual. The developer says this is due to developer tools that will not be in the final release.
The Wallet TrackR represents an evolution in development, dating back to an original 2009 Bluetooth-based design. Because regular Bluetooth has much different power consumption characteristics, the initial system had only a one week battery life. "It was really a big black ugly thing," explained developer Chris Herbert. "We got it to market and had some initial success, but BLE was the tech we were waiting for."
Phone Halo plans to ship units in April 2013. They will cost US$49.95 per device, although you can pre-order now for just $19 each in a sort of non-Kickstarter Kickstarter campaign. Herbert explains that the company will not charge cards until the units are ready to ship.