Product Description Just touch the Cooper Bussmann fuse tester's prongs to the contacts of the fuse. If the light goes on, the fuse it good; it's that simple. Test any marine, motorcycle, RV or truck fuse. From the Manufacturer The Bussmann Fuse Tester has a 24-volt maximum. It tests automotive, glass tube and ferrule fuses up to 1-7/8 inches in length. Batteries are included. UL listed. Bussmann is North America's leading supplier of fuses and fusible protection systems. You can be assured of the utmost quality in every Bussman product.