An LED ring on the bottom of the alarm also changes color, giving you a visual cue. The Nest Protect comes in both wired and battery powered versions. If you have more than one in your home, and one goes off, the others will too, alerting you to the location of the fire. The Nest Protect also works with a wide range of smart home devices. For example, in the event of an emergency, the Nest can automatically turn on your lights, making it easier for you to get out of your house. What Owners Are SayingOn Best Buy, the Nest Protect has an average rating of 4. 8 stars from more than 1,200 reviews. While many acknowledged its high price, most complimented its performance, compatibility with other smart home devices, and built in night light. ""What I personally like is the ability to know exactly where smoke would be coming from. If I were to be on the fourth floor in the middle of the night, it would say 'there is smoke in the living room'," wrote one reviewer. 99 View at eBayCheck WalmartCheck Amazon?The Roost battery is the best — well, only — option for those who already have smoke detectors, and want to make them “smart.