TOOGOO(R) Battery Terminal Link Switch Quick Cut-off Disconnect Car Truck Auto Vehicle Parts Black(Battery switch 4) Made of brass plated zinc alloy. Good conductivity, stable performance. Easy operation: disconnect and reconnect battery by one simple turn of the knob on it. Effective to solve theses problems: electric leakage and loss of electricity. Corrosion resistant. Fit for different types of batteries and the diameters their pile heads are 10mm.