The SportDog SD-425 Field Trainer is the perfect electronic collar for training a dog in the yard or out in the field. Both the transmitter and receiver are completely waterproof and submersible. The SportDOG 425 can be expanded to control up to 3 dogs and has a 500-yard range. It features 7 instantly selectable stimulation levels and also has tone or vibration function available with different button configurations. The comfortable 'soft coat' transmitter finish makes this unit a pleasure to handle.