Function: when dog bark for once, the stopper produces short warn sound; If dog continues to bark within 30s, it will produce stronger warning sound and short, soft electric shock; If the dog is still barking, warning sound will be louder and shock be stronger. The 3-mode can be repeatedly used. If all 3-mode are failed, the stopper will produce the loudest sound and the strongest shock till the dog stop barking. After stop barking for 30s, the stopper can auto set to the first warning sound. Thus your dog can remember the punishment and reduce barking gradually. This is very efficient.