For DC negative ground electrical systems. Isolate each battery to prevent the battery with the higher charge from draining into the battery with the lower charge. Allow two batteries to be charged simultaneously from a single power source. 90 Amp rating per leg, 2 legs. Three 1/4″ stud terminals, 6-1/2″ L x 3-1/4″ W x 2-13/6″ H.