Use these Fuse Blocks with the class R 250-volt Fuses. Bare wire ends fit into the screw terminals on each end of the fuse block. The small fuse block holds 10-30A fuses and accepts up to #2 wire. The medium size block holds 40-60A Fuses and accepts up to #2 wire also. The large size block holds a 100A Fuse and accepts up to #1/0 wire. Small and medium size blocks are available in 1-pole and 2-pole versions.