4pcs 2.4G WiFi Wireless Window Door Smart Contact Sensor Kit For Home Assistant
SMART HOME SECURITY SENSOR: 0.78 IN wide gap allowed. Without tools, Easy to install the window sensor with the included sticker, firm and durable. You can install the door sensor on front doors, garage doors, liquor cabinets, windows, pet doors, and more. The contact sensor is also a good option as a mailbox sensor.
LOW POWER WARNING AND SERVICE: The sensor door needs TWO AAA Batteries(Not included). When the battery is running out, you will receive an App notification, Don't worry about missing any moment.