Dogtra Gold 2 Dog 1/2 Mile Remote Trainer 202NCP Pet-trainer or sporting dog unit for mild-mannered to medium disposition dogs. Rheostat dial that allows for gradual increases in stimulation intensity with no jumps between level Two-dog models allow the trainer to control two different dogs from one transmitter Waterproof collar/receiver and waterresistant transmitter Rechargeable, user-replaceable Ni-MH batteries