Instruct: Classify the given Amazon review into its appropriate rating category
Query: It works, but...

The collar works, but the prongs must be situated right under the dog's mouth. If it strays even a half inch in either direction, the collar doesn't detect any barking - even on the highest sensitivity level. I have the collar really tight and it still swivels. I'm afraid to make it any tighter. The prongs are already digging into him.