The H2O 1800 series is a great collar system that can be used in a wide variety of applications. This fully waterproof unit covers both basic and advanced training needs for both professionals and novice users alike. Whether you are knee-deep in cold icy waters or knee-deep in tall grass on a dry sunny day, the H2O is designed with the harshest environments in mind. The D.T. Systems H2O-1800 series has an 1800 yard (1 mile) range. Comes with completely waterproof and rechargeable (Ni-MH batteries) transmitter and collar units. H2O1810-PLUS Nick or Continuous stimulation. -Vibration stimulation (with stimulation or vibration only. Features: 1800 Yard (1 Mile) 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. Gentle Touch System Extra Mild Stimulation. Built-In Safety Shut-Off. Rechargeable Ni-MH Battery System. Completely Waterproof Transmitters and Collars.