Nest's Protect smart smoke and CO alarm has been getting better with age thanks to software updates, but now it's time for a hardware upgrade. Nest has just announced a brand new Nest Protect, with improvements in both the hardware and software department. For starters, it's loaded with what Nest call a "split-spectrum sensor," which is said to be better at detecting both fast-burning and slow-spreading fires than the photoelectric smoke detector the first-gen Protect uses. A new smoke chamber also greatly reduces the chance of false-positive alerts due to dust or bugs. Also, you can now test the device's speaker, horn and its sensors from within the companion app, as well as silence the smart smoke detector's screams from your smartphone when you burn your dinner.