THE H20 1820 PLUS EXPANDABLE SYSTEM allows you to add collars to control up to 3 collars. 16 adjustable intensity settings from the lightweight waterproof transmitter. Nick, Constant stimulation and Positive Vibration modes. Rechargeable NiMH batteries in both the transmitter and collar. Storage case included. One mile range with Maxx-Range� embedded antenna. 1 yr. mfg. warranty. Limited Lifetime warranty against defects.