18N BB CHUCK 1-piece fluted sleeve constructionBall trust bearing reduces friction in chuck closing mechansimThrough-hardened sleeve teeth, nose, and keyholes for wear resistantMaximizes gripping force and drilling accuracyTreated to ensure thread life and high gripping surface hardnessJaws center-ground for absolute straightness and alignmentFor heavy-duty, close tolerance production drillingFor production drilling equipment, jig borers, milling machines, lathes, and radials Bit/Blade Mounting Size 1/8 in Min , 3/4 in Max Overall Length 3.950 in Min , 5.120 in Max Capacity 1/8 in mild steel Min , 3/4 in mild steel Max Finish Fluted SleeveHousing Diam 3 inKey Size K4Mechanism Ball BearingMounting Jacobs 4JT FemaleType KeyedWt. 66 oz