The iDT Add-On Collar unit can be added to your Micro-iDT PLUS training system to expand your unit up to a 3-dog system. This Add-On Collar can also replace a lost or damaged collar for MicroiDT Z and PLUS series systems (only for systems with serial numb Lightweight and waterproof 16 levels of intensity, adjustable from the transmitter Vibration feature Expandable up to 3 dogs Up to 900 yard range
