'Drill Bushing, Headless Press Fit, Inside Dia. 0.129 In., Outside Dia. 5/16 In., Inside Dia. Tolerance .0001-+.0004 In., Outside Dia. Tolerance +0.0013 - +0.0016 In., Concentricity Tolerance .0003 In. T.I.R. Max, Overall Length 1/2 In., Material 52100 Thru Hardened, Finish Steel, Drill Size #30, Hardness RC 62-64'