E-Z Drill bushing sizes correspond with hole diameters. For example, a 7/8-inch bushing (1110 MCP) fits a bit that drills a 7/8-inch hole. It will not, however, work with a "7/8-inch steel" or "7/8-inch hex shank" since these pieces reference the shank size, not the hole size. Consult our "Drill Bits and Drill Steel" chart on any drill model page for size requirements.