MERSEN class R fuse blocks accommodate 250 and 600 V 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 2500 V. 30, 60 and 100 A fuse blocks feature a unique adder block which can be snapped onto 1-, 2- or 3-pole blocks to form multi-pole segmented blocks of as many poles as desired. All fuse clips are made of high conductivity tin plated copper, with a choice of spring reinforced or non-spring reinforced clips in 30 and 60 A. Clips 100 A and above are spring reinforced.