The Compact, Lightweight Micro-iDT Training Collar! A lightweight trainer that offers simple controls, but advanced features so that this unit can grow with your dogs training needs. The rugged micro-sized collar unit and transmitter fit in the palm of your hand. The comfortable waterproof collar fits small to large dogs: Features: 900 Yard Range. Supports up to 4 dogs (Add-On Collars Sold Separately). 16 Levels of Intensity adjusted from the Transmitter. Digital Technology to Maximize Power. Maxx-Range Internal Collar Antenna System. Lightweight, Compact Collars and Transmitters. Fits extra-small to large dogs. Built in Magnetic ON/OFF system. Completely Waterproof Collars. Weatherproof Transmitters. Rechargeable Ni-MH Battery System in the collar. Positive vibration available.