An E-Collar is a remote dog training system that consists of a wireless remote and wireless receiver. E-Collars allow you to remotely send signals to your dog to help them understand "good behavior" and "bad behavior". The different E-Collar models you can select from have functions that allow you to send either a tone, vibration, or a stimulating sensation to the dog (similiar to a Tens Unit for muscle stimulation). Improve your relationship with your dog(s) and unleash their full potential!