If you're passionate about IT and electronics , like being up to date on technology and don't miss even the slightest details, buy Sensor Eufy T89000D4 at an unbeatable price. Characteristics: Wireless Battery operated Battery operated: Yes 1 Litio Ion Type: Wireless Width: 28 mm Colour: White Batteries included: Yes Battery type: CR123A 2-YEAR BATTERY LIFE: One CR-123A battery provides monitoring for 730 days.FOR DOORS AND WINDOWS: Small and compact design fits onto any door or window frame.100-DECIBEL SIREN: If a forced entry is detected, a siren as loud as a jackhammer will be triggered on HomeBase, and you’ll be notified instantly on your smartphone.EASY INSTALLATION: Just peel off the mounting tape and stick the sensor onto the door or window you want to monitor. Connectivity technology: Wireless Product colour: White Battery type: CR-123A Number of batteries supported: 1