This remote control works exclusively with our Wireless Motion Detector with remote (item HS4340D) and  Remote control / Wireless Ceiling Alarm  ( item HS4900D).  The extra remote control will allow an additional user to arm and disarm the alarm as along as the codes are set correctly.  With the included keyring you always know where the remote is located.   This remote will allow you to turn the alarm / chime on / off up to w5 feet away.  The remote measures 2 1/2 inches x 1 inch x 3 /8 inches and requires 2 -1.5 volt button cell batteries that are included.