The Micro-iDT PLUS is a lightweight trainer that offers simple controls, but advanced features so that this unit can grow with your dog's training needs. This system can expand to a 2-dog or 3-dog system. The rugged micro-sized collar unit and transmitter fit in the palm of your hand. The comfortable waterproof collar fits small to large dogs.FeaturesExpandable to 2-dog or 3-dog system with Add-On collars 900 Yard (1/2 mile) Range 16 intensity levels of Nick and Continuous stimulations adjusted from the Transmitter Positive Vibration for a "no shock" alternative training methodDigital Technology to Maximize Power MAXX-Range Internal Collar Antenna SystemExtra mild Gentle Touch Stimulation SystemLightweight, Compact Collars and Transmitters Fits small to large dogs--collar adjusts from 7" to 22"Built in Magnetic ON/OFF system. Rechargeable and Completely Waterproof Collars Ni-MH Rechargeable battery included in Collar Weatherproof Transmitters with No-Sli...