Our ultrasonic remote trainers can be used to teach your dog without using a receiver collar to train. The ultrasonic remote uses two different types of tones, one that is a positive tone for when your dog does something you are proud of and obeys, and the other negative tone used when your dog has misbehaved and is using behavior you do not want him to use. The negative tone is a tone heard only by your dog but is annoying and distracting to your dog to catch his attention and cause him to stop his unwanted action.