The Pet Corrector helps stop: Barking, Chasing, Stealing, Jumping Up, Place Avoidance and other unwanted behaviours. It works by emitting a hiss of compressed gas to interrupt a dog’s unwanted behaviour. The overall effect is to grab the attention of a dog. It is used and recommended by trainers and behaviourists throughout the world and over 3.5 million have been sold to date. It is recomended that you read the user guide (supplied free with this product) prior to use. The Pet Corrector comes in 3 sizes: 30ml, 50ml, 200ml and a holster for the 50ml size.