"NOVA IENS 1-Inch 10TPI Chuck Insert/Adaptor allows you to 'adapt' your Insert Type NOVA Chuck to a 1-Inch 10tpi Lathe. Allows you to keep the same chuck and accessories if you change your lathe - you only need to change the insert/adaptor. The internal thread is 1-Inch 10tpi and the external thread matches the NOVA insert type chucks, to simply and easily screw into the back of your NOVA Insert Type Chuck. This then makes your NOVA insert type chuck ready to attach to your 1-Inch 10tpi threaded lathe spindle. Precisely machined from 1045 High Tensile Steel. Designed by the innovators of the 4 Jaw Chuck for wood turning, Teknatool International - since 1955. Backed by a full replacement 2-year warranty."