Instruct: Classify Amazon reviews into positive or negative sentiment
Query: good but needs base

Overall works great, but the bottom relies entirely on the width of the AA battery to make contact. So, if you have a flashlight or other device with a spring at the bottom, many are wider than the width of a AA battery and don't make contact with the AA battery base. Some other AA to D converters have a plate on the bottom of the case to make it the width of a regular D battery that the bottom of the AA battery would contact, hence making good contact regardless of the contact method in the device you are using them in.