Micro-iDT ADD-ON or Replacement Collar Choose: Color Make your Micro-iDTPLUS a multi-dog system Add-on or Replacement Collar/Receiver for the Micro-iDTPLUS. Available with your choice of Black, Orange, or Green collar straps. Black is recommended if you need to replace the original collar/receiver that came with your Micro iDTPLUS system. Orange and/or Green are recommended to expand your IDTPLUS unit to a 2-dog or 3-dog system. Features Lightweight Waterproof 16 levels of intensity, adjustable from the transmitter Nick and Continuous Stimulations Vibration feature MAXX-Range Internal Antenna System Rechargeable Ni-MH Batteries Available with Black, Orange or Green Strap