I know they have the voltage on the label and sometimes the polarity but it's not enough. Why don't they have an easy way to identify which adaapter goes with which component. I have two 100k spot lights and can't figure which adapter will charge them. I somehow misplaced the original so I bought another and now can't figure out which one it is. I have too many from over the years of drills, dvd players, battery jump starters, razors, etc. Maybe put the name of the device on the label or something color coded.

match the connectors first then look at the voltage on the wart, usually there is a molded polarity and voltage next to where it plugs in.

Remember, just because it fits in the hole, doesn't mean it belongs there.

Be careful about checking the voltage and Amp rating on the power supply. The voltage on the supply must match the exact voltage requirements of your device. The amp rating must be higher than the requirements of the device.