The world's smallest and most versatile no-bark trainer. This anti bark collar helps your dog learn the difference between good barking (for protection) and bad barking (prolonged and loud). The anti bark collar picks up the vibrations from your dog’s vocal chords as it barks. The vibrations cause the anti bark collar to send an electronic signal (a static shock) to your dog. Your dog will quickly learn that barking causes the signals, and that not barking is the way to avoid the signals.Vibration Sensor only picks up vocal cord vibrations eliminating unnecessary shock from extraneous noises or dog's tags. Adjustable Collar fits extra small to extra large dogs. ULTRA MIN-E 2090 Anti Bark Collar corrects unwanted barking in dogs as small as 3lbs up to 40lbs. DT Systems Ultra e 2090 is a waterproof battery replaceable collar.