Instruct: Classify the given Amazon review into positive or negative sentiment.
Query: Useful Charging Device

I purchased this charger specifically for the Sony HVLF32X photo flash. It works very well except that the charging time is very long.The manual also recommend charging batteries only after they are completely empty but it does not tell how to be sure that this is a fact.Nonetheless, I have to specifically mention that this device works with any voltage and could be used on international trips without any additional adapter (of course one needs a simple adapter for plugging this charger into outlets of different configuration - the item that could be easily found on the web or in Radio Shack stores). It is also very convenient that the same charger works with AA and AAA batteries