The GEM-PIRPET is an advanced Pet Immune PIR sensor designed for use with NAPCO's GEM-Series wireless receivers. In normal operation, the GEM-PIRPET will avoid detection of pets up to 40 lbs. total weight or 24" tall. The unit is powered by two 3-volt lithium batteries (supplied) for long service life. When battery voltage drops below normal, a low-battery report will be sent to the receiver. (replace with Duracell DL123A or Varta/Power-One CR123A only). Coding switches are not used in the GEM-PIRPET. Each transmitter has a unique factory-programmed RF ID code (printed on the unit) that distinguishes itself to the receiver. (Note: See control-panel instructions for enrolling the GEMPIRPET into the panel).