G2747 Drill Bushing Bushing Type Head Press Fit H Inside Dia 4.55mm Outside Dia 5/16 In Inside Dia Tolerance +.0001- +.0004 In Outside Dia Tolerance +0.0016 - +0.0013 In Concentricity Tolerance .0003 In T.I.R. Max Overall Length 3/8 In Material 52100 Thru Hardened Finish STEEL Drill Size 4.55mm Hardness RC 62-64