Weiler 56490 Mandrel For Type 1 Cutoff Wheels, 1/4" Diameter Shank, 3/8" Arbor Size Mandrel mounts a Type 1 cutoff wheel with a 3/8" arbor hole onto a grinder that accepts a 1/4" shank Fits 0.035"- to 1/4"-thick wheels Carbon steel provides strength for extended tool life