MTP Large 4 Way Chuck Key Drill Press 3/8", 1/2", 3/4" & 1" Universal Combination #6 , #7, #8, #9, Chuck size:3/8" (10mm) , 1/2" (13mm) , 3/4" (19mm) and 1" (25mm) 4 way chuck key small: 5, 6,7,8 Dropped forged alloy steel. Chuck size:3/8" (10mm) , 1/2" (13mm) , 3/4" (19mm) and 1" (25mm)