The 3. 2 inch sensor also features a nearby magnet; open the door or window, and a magnetometer in the Detect is triggered, sounding the alarm. In a particularly handy feature, there's a button you can press on the Nest Detect that disarms the sensor so you can open the door without bothering everyone in the house with an alarm; the sensor rearms when the door is shut. Nest DetectThe final piece of the puzzle is Nest Tag, which attaches to your keyring. It allows you to tag in and out of the house for those times you don't want to fiddle with the keypad on the Nest Guard. Nest executives stress that the 1. 46 inch circular Nest Tag is pretty durable, capable of surviving a trip through the washing machine if you forget to remove it from your pocket. In addition to the keypad on the Nest Guard and the Nest Tag, there's a third way to arm and disarm the system — an app on your phone. The app will even send you a reminder to remotely set the alarm when you leave the house. The app's also where you'll get security alerts whenever the alarm goes off. Nest Detect, attached to a doorNest executives say they designed the Nest Secure system with the people who live in a home in mind as much as the burglars trying to break in.