Honeywell 5818 Recessed Door Contact
The 5818MNL is a magnetic contact sensor that provides concealed protection for doors or windows.
The 5800 Series of door and window transmitters provide the most reliable, convenient and cost effective solutions for security protection. These devices are powerful and versatile enough to help solve even the toughest, most labor intensive installations.
With a demonstrated outdoor range of over a mile, the 5800 Series has the best performance of any transmitters available today.