This lead is useful if you have more than one vehicle that you wish to use your Accumate charger on.
Connect the ring terminals to the battery and tuck the black SAE connector out of the way until you need to use the Accumate, when it can then just be plugged in.
If several vehicles have one of these connecting leads, then the Accumate can be easily moved between vehicles to keep them topped up! Easier than trying to find the battery in order to charge the battery.