Instruct: Classify a given review as either positive or negative.
Query: Pretty good, but be gentle

I acquired about a thousand used AA batteries from a hotel project, and bought this to test for the good ones. Worked great for a few hundred of the batteries, but then broke the first time I put a battery in backwards... one of the copper contacts snapped right off. :(My fault, but still... the contacts are pretty delicate. Four stars for that. I managed to bend the rest of the contact upwards and the unit still works, and in fact now works better because the batteries aren't restrained in the unit anymore, they go in and come out faster than previously.A good unit for the money... just be careful putting the batteries in!