About This [EXPAND WAVELINK FOSMON DOORBELL SYSTEMS] Perfect solution for expanding your Fosmon Doorbell System with this additional door sensor transmitter. Compatible with: 51004HOM -Fosmon WAVELINK Wireless Entry Alert Doorbell 51005HOM - Fosmon WAVELINK Wireless Motion Doorbell Alert Sensor 51007HOM - Fosmon WAVELINK Wireless Door Open Chime 51009HOM - Fosmon WAVELINK Wireless Entry Alert Doorbell (Black) [MODERN AND CONTEMPORARY DESIGN] Never miss anyone at the door. The wireless and portable design works well in home, work, retail stores, salons, and business environments. [MAGNETIC DOOR SENSOR] With your Fosmon WAVELINK doorbell system installed, this magnetic door sensor activates when the magnetic stripe is separated notifying the receiver when the door has been opened. [BUILT-IN LED INDICATOR] The transmitter features an LED indicator that creates a visual alert for the hearing impaired. [EASY TO INSTALL] Wire free and easy to install. Overview Color : 4 PACK Brand : Fosmon Power Source : Battery Powered Compatible Devices : 51004HOM, 51005HOM, 51007HOM, 51009HOM Product Dimensions : 2.95"L x 1.97"W x 0.63"H