G4646 Drill Bushing Bushing Type Headless Press Fit Inside Diameter 1/4 In Outside Dia 1/2 In Inside Dia Tolerance .0001-+.0004 In Outside Dia Tolerance +0.0014 - +0.0017 In Concentricity Tolerance .0003 In T.I.R. Max Overall Length 3/8 In Material 52100 Thru Hardened Finish Steel Drill Size 1/4 In Hardness RC 62-64