Ting
Received one by signing up on State Farm for free. Not sure if I want to actually use it, especially when linked to home insurance.
You can buy one on eBay, because they have a subscription, so I suppose many people don't want them any more.
Hardware
Plastic shell with a button on the lower-left edge and LED indicator in the center of the lower black portion. Plugs into a USA 120V 3-prong outlet.
The back half overlaps the front half. There are three notches with clips on each side, and one on top, one on bottom. Prying these popped it apart.