This Oil/Fuel gauge allows you to check the level of liquid in the oil or gas tank of your bike. Includes a ring with an outer diameter of 50 mm and that is 8mm high. Made out of good weldable steel, as the ring needs to be welded onto your tank. Then screw the brass ring (approx 38mm round)with the sight glass, in the welded ring. The brass ring has a seal so that no leakage occurs.