DT Systems Add-On or Replacement Training Collar Receiver, Black Maxx-range internal antenna system in collar belt smartled light on collar receiver Lightweight, compact, completely waterproof collar and transmitter Rechargeable ni-mh battery system Built in safety shut-off system Up to 900-feet range Lightweight and waterproof 16 levels of intensity, adjustable from the transmitter Vibration feature Expandable up to 3 dogs