Mersen class R fuse holders accommodate all class R power fuses. A choice of screw, pressure plate, box and special order stud connectors fit a wide range of stranded or solid copper or aluminum wire. Insulators are either molded glass filled polycarbonate (GFPC) or phenolic with verified dielectric strength in excess of 2500V. 30, 60, 100 and 200A fuse holders feature a unique adder block to form multi-pole segmented blocks of as many poles as desired. All fuse clips are made of high conductivity tin-plated copper.