Mersen 20311 - Mersen Class H, K and R fuse blocks accommodate all Class H, K and R 250 and 600V 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 and 100A fuse blocks feature a unique adder block which can be snapped onto 1-, 2- or 3-pole blocks to form multipole segmented blocks of as many poles as desired.All fuse clips are made of high conductivity tinplated copper, with a choice of spring reinforced or nonspring reinforced clips in 30A and 60A. Clips 100A and above are spring reinforced.