There are different types of collars. There is one that we have used on our Lab, it does not shock or anything else that is hurtful. It emits a high pitch noise that dogs can hear that they find irritating, it emits when they are 'nuisance' barking, not alarm barking. When we bought ours (about 5 years ago) they were about $10. I think it might of been from Carol Wright but not positive.