Here's the problem I have with it: 4.6 x 2.3 x 1.1 inches. That's an awful big object to be sitting in the exposed sunlight. Chances are it'll be laying on the ground somewhere. Generally if you haven't recovered your bike within 24 hours it's gone forever.
The better trackers go into the stem if a threadless head set or in the seat post tube. There's also alarms and cellphone notifiers one can get. However these devices are complimentary items. They aren't ment to replace locks and common sense. One should always use both a 15mm+ keyed cable and U locks. A quality set of locks will cost around $70.
Don't leave your secured bike unattended in public any longer than you have to. Always store your bike in a secure structure. When I'm done riding for the day my bike comes in my house.
