4-3/4" diameter x 2" high magnetic chuck with handle. The back has a 4" bolt pattern and a 3" bolt patter with a 2" (50.84mm) pilot diameter. The bolt holes are tapped for 6mm bolts. Stamped on the chuck: ECLIPSE MAGNETIC LATHE CHUCK MADE IN ENGLAND CAT. No. AX475C. This Chuck has a strong magnet and smooth mag action.