Micro-iDT PlusFeatures:- Digital Technology- Up to 900 yard (1/2 mile) range- Expandable to 3-dog system with Micro-iDT add-on units (sold separately)- 16 Adjustable levels of Momentary (Nick) and Continuous stimulations- Positive Vibration- Lightwieght waterproof rechargeable collar unit- No-slip/soft-grip weather-resistant transmitter- Patented MAXX-Range internal antenna system- Built-in safety shut off- Transmitter takes 9 volt battery (Not Included)Comes with: - Transmitter- Receiver Collar- Battery Charger- Adapter/Splitter Cable- Test Light