G8624 Drill Bushing Bushing Type Slip Fixed Renewable Combination SF Inside Dia 4.5mm Outside Dia 5/16 In Inside Dia Tolerance .0001-+.0004 In Outside Dia Tolerance -0.0005 - -0.0007 In Concentricity Tolerance .0003 In T.I.R. Max Overall Length 1/2 In Material 52100 Thru Hardened Finish Steel Drill Size 4.5mm Hardness RC 62-64