SportDOG Additional Collar is compatible with the SportDOG Contain + Train SDF-CT-22 system. Add an unlimited number of dogs to the fence system. Train up to 3 dogs. Fits adult dogs above 15kg. With 3 operational modes, you can control which part of your Contain + Train system the collar responds to. The collar can easily be set to respond to only the Remote Transmitter, only the Fence Transmitter or both. In Training Mode, use your Remote Transmitter's dial to select one of the 7 levels of static stimulation in either low, medium or high ranges and use the buttons to deliver your choice of momentary (nick) or continuous stimulation. You also have the option to train with vibration (buzz) and tone (beep). In Containment Mode, the collar will give a warning tone and vibration as your dog approaches the boundary and then moves to one of 7 static stimulation levels that you select, based on your dog's temperament.