NOVA 10006 Safe Lock Woodworm Screw Chuck Accessory comes standard with most NOVA Chucks but is also available as a separate purchase. Suitable for NOVA Chucks. Quick and easy method to mount small bowls blanks. It provides a secure mounting to form the outside of bowls. Strong thin edged thread form design to cut into wood and hold on. Square shank for strong and positive location into the chuck body. Designed by the innovators of the 4 Jaw Chuck for wood turning, Teknatool International - since 1955. Backed by a full replacement 2-year warranty.