DT Systems Micro iDT Plus Add On Training Receiver Collar: * Can be added to your Micro-iDT Plus training system to expand your unit up to a 3-dog system * Can also replace a lost or damaged collar for MicroiDT Z and Plus series systems (only for systems with serial numbers that start with a letter) * Fast and simple programming into your system * Digital technology * Up to 900 yd (1/2 mi) range * Lightweight and waterproof * MAXX-Range Internal Antenna System * Rechargeable Ni-MH batteries * Built-in safety shut off system * Includes 1 collar unit with a collar belt