WIRING HARNESS RING LUG CABLE. It is a ring lug cable that screw mounts onto a battery and provides an interface for plugging into a charger, dc socket, etc.
WIDELY USED. This is the best way to keep a battery charged on a Motorcycle, Boat, Cycle, Bike, Car, Tractor, Riding Mower, ATV, every vehicle outdoor equipment.
Convenient for hard-to-access batteries. Used for most maintenance battery chargers such as Battery Tender, NOCO Genius, Schumacher, Black & Decker and so on.
For most battery Trickle Chargers that use the male female plug (SAE). Fast and easy to connect and disconnect.