The PG9936 works on the 915 MHz frequency, can be mounted on a wall or ceiling, and comes with the hardware to do so. Just as every PowerG device; the PG9936 features mutli-channel frequency hopping to help prevent frequency blocking and interference. It also uses 128 bit AES encryption to provide protection against analysis tools and digital attacks. Another preventive measure this contains is a back tamper in case someone tries to remove it from its mounting position. The PG9936 uses 3 AAA batteries for power which will last an average of 3 years and measures in at 5 x 2.5 in.