The DT Systems SPR5100 E-collar delivers top-tier performance for serious trainers with a 2-mile range and waterproof, rechargeable design. 2 mile range Waterproof collar and transmitter Rechargeable Li-Poly batteries SmartLED battery indicators 24 stimulation levels High-Med-Low Instant Stimulation buttons LCD screen on transmitter Expandable up to 4 dogs, add additional collar with item 748051