This is pretty brilliant. It's a rechargeable battery that can connect to WiFi, and send alerts to your smartphone through the web. Pop it into your smoke alarm, and voila; you've got a smart smoke alarm. It's also WAY cheaper than Nest Protect

Another interesting note: it also uses the yet-to-be-finalized 802.11ah low-power WiFi standard

this is pretty cool. i love that i don't have to replace my existing smoke alarm to use it!