The PetSafe UltraSonic Remote Trainer PUPT-100-19 is a hand-held device that uses two (2) different tones for correcting and rewarding behavior. There is no collar needed with this trainer as it works on ultrasonic tones emitted from the hand-held transmitter. It has an effect range of 30 ft. so it can be used indoors as well as outdoors when in close proximity to your pet.

Note: There is no collar with this trainer, the tones (Corrective and reward) that are emitted and audible by your dog.  Very effective for close range training and works well indoors as a communicative device.