The CA-SOS Button is part of the CentralAlert Notification System by Serene Innovations. Small and waterproof you can carry it with you and signal the CA360 or CA-RX receiver from anywhere in the home when you need assistance. Features Water resistant design. 2.4GHz Smart-Code technology. Up to 200 ft operating range. Four CA-SOS units supported. Uses one button 2012 battery (included). Dimensions: 3.25 x 1.5 x 1 in. Item Weight - 1 lbs.