Instruct: Classify Amazon reviews into positive or negative sentiment
Query: Great, informative battery meter

I bought this meter on the recommendation of photographer Ken Rockwell (kenrockwell.com). It tells you how much power is left in the battery (0, 20%, 40%, 60%, 80% or 100%) rather than just "good" or "bad." I can't claim that I've saved a lot of money left, but I've only had it a few weeks.