Reliable dog training system performs effectively in all environments and climates. Features 7 unique training modes to meet specific training needs and 8 levels of continuous or momentary stimulation. Provides consistent stimulation on land and in water within a range of 3/4 mile (1300 yards). Expandable to a 2-dog system with an additional receiver. Waterproof receiver operates on a Ni-MH rechargeable battery (battery and charger included); water-resistant transmitter requires a 9V battery (not included). Collar fits 9in.-22in. necks. Limited lifetime warranty.