Instruct: Classify the given Amazon review as either positive or negative.
Query: simple display of battery condition

This is the cheapest and simplest device for making sure your battery is at its proper voltage. A necessity for anyone wanting to pull electricity from a battery while the engine is off. It is not bomb proof, however.... My first one broke after leaving in the glove compartment, where it got knocked around by the items in there. The swivel is where it broke, and the circuitry eventually failed causing the screen to go blank. Keep it protected and it will last. Fortunately it doesn't cost much to replace.