When you leave home, your Smart Home Security system can remind you about doors or windows that were left open. With highly sensitive detection and tamper-proof smart technology, you'll know when a door or window is opened even slightly, so you can rest assured knowing your home is secure. 1) Communicates wirelessly and efficiently using Honeywell Secure Wiselink Protocol. There are no screws or wires, just simple and fast installation. 2) The battery lasts up to 4 years so you rarely have to worry about changing it. 3) Detects movement of less than an inch so you know when a window or door is open even slightly.