Trainer is for small dogs 8 lb. to 40 lb. Collar adjusts approx. 3 1/2' to 5 1/2' in dia.  Has a 100 yard range. Works on impulse our sound. There is $9 worth of new batteries in it. I purchased it new for $130 receipt in manual used it 2 times and it sat on shelf till batteries went dead. In like new condition.