This is a rugged, 4-pronged Spur Drive with a 19mm square shank which fits snugly into the Nova Chuck Jaws.
Creep of the Spur is prevented as the shank is slotted to allow the chuck jaws to close over it. The design takes quite a novel approach with points located at each corner. The wedged shape of the prongs allows them to penetrate and firmly grip the wood.
The spur is just the answer for turners who use the Nova Chuck most of the time but want to be able to swap quickly for spindle work.
Shown illustrated mounted in chuck with 2″ jaw set.