Dieter Bohn, writing for The Verge:
At an event today in San Francisco, Nest announced that it is releasing a second-generation smoke detector, and it’s also called the Nest Protect. The new detector has a “split spectrum sensor” for smoke detection, a step beyond the single photoelectric in the original one.
It’s 11 percent smaller than the original, can test itself automatically with its speaker when it thinks your not home, is easier to install, and features a smoke chamber that keeps dust and insects out. It’s available for preorder today for $99 and ships at the end of the month.