This universal sensor has 1 built-in reed switch plus 2 external zone inputs (open or closed circuit) which allows it to secure up to 3 doors, windows, etc. It also features Elk's industry leading two-way technology.

Features:

• Compatible with ELK-M1XRFTW(M) two-way wireless transceivers
• Zones: Built-in reed, IN1, and IN3 (external contact terminals)
• Front and back tamper option

What's Included:

• Universal Door/Window Wireless Sensor
• Magnet
• Replaceable 3V Lithium battery
• Tamper Switch
• 4 #4 x ½” Flat Head Sheet Metal Screws
• Double Sided Tape for both transmitter and magnet
• Instructions