NOVA IDNS 1-Inch 8TPI Chuck Insert/Adaptor you to ` adapt ' your Insert Type NOVA Chuck to a 1-Inch 8 Lathe. you to keep the unvaried chuck and accessories if you change your lathe - you solely need to change the insert/adaptor. The inner thread is 1-Inch 8 and the outward thread the NOVA insert type chucks, to plainly and easily screw into the back up of your NOVA Insert Type Chuck. This then your NOVA insert type chuck set up to attach to your 1-Inch 8 rib lathe spindle. Precisely from 1045 spot tractile Steel. by the innovators of the 4 Jaw Chuck for wood turning, Teknatool International - since 1955. by a whole replacement 2-year warranty.