G8634 Drill Bushing Bushing Type Slip Fixed Renewable Combination Inside Diameter 0.159 In Outside Dia 1/2 In Inside Dia Tolerance .0001-+.0004 In Outside Dia Tolerance -0.0002 In Concentricity Tolerance .0003 In T.I.R. Max Overall Length 1-3/4 In Material 52100 Thru Hardened Finish Steel Drill Size #21 Hardness RC 62-64