Groz Engineering Tools [P] Ltd manufactures Hardened Hi Tensile Steel made Drill Chuck Arbors. Groz Engineering Tools [P] Ltd. Is an ISO 9001:2000 certified company. The Hardened Hi Tensile Steel made Drill Chuck Arbors are used to mount a drill chuck or any other tool which has a female taper/straight shank onto a machine such as a drilling machine which has a female taper/straight shank socket in its work head. The Hardened Hi Tensile Steel made Drill Chuck Arbors are case hardened to 54-58 HRC for increased resistance to wear. Precise grinding to very close tolerance with concentricity controlled to within 0.0004" [10 microns] and accurately gauged self locking tapers ensure close tolerance fit.