The transmitter will NOT function as a second transmitter with your system. The beeper horn is built into the receiver and eliminates the bulky horn that sits on top of your dog's head like other beeper units. For dogs 20 lbs or greater. The unit features 2-hour rapid charge Lithium Polymer batteries. Fully waterproof collar/receiver and transmitter. LCD screen displays exact level of stimulation even in dark or low light conditions. Three bar battery life indicator. Precise stimulation level (0-127) 3/4 mile range 'Nick', 'Constant' and non-stimulating pager/vibration High and Low tone beeper (Single-dog unit only) Three beeper modes 'Run and Point', 'Point Only', and 'Locate'