A perfect match for the SK80 chuck these popular C jaws feature three separate gripping methods. An external dovetail which opens into a 50mm recess, a 40mm internal diameter stepped shoulder for a firm grip on the outside of a spigot. A screw chuck can be purchased separately for use with these jaws. Recommended range: 35-55mm internal, 50-70mm external. Although designed to fit the 80mm chucks these jaws will also fit the 100mm versions.