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. System includes: one transmitter, two receiver collars, a battery charger and splitter cable, a test light, an owner's manual and a carrying case.