The FieldTrainer® 400 Series of electronic remote training collars from SportDOG Brand® is loaded with technical breakthroughs in the smallest package available in this price range. Features such as 3-dog expandability and waterproof/submersible transmitters and receivers are among the most advanced benefits ever offered in a mid-range remote training system. With 400 yards of range, these palm-of-the-hand sized models are designed for field training and hunting with close-working dogs.