Guest Extra-Duty On/Off Diesel Power Battery Switch [2304A]Extra Duty On Off Diesel Power Battery Switch 3 studs heavy duty diesel power battery switches are built with heavy duty copper sweep contacts to ensure positive circuit control. Rugged internal components are protected by a tough, impact resistant polycarbonate housing that is impervious to the elements. They also feature Alternator Field Disconnect (AFD) allowing selection of any position, including "off", without damage to the alternator or