These feedscrews are for old style 16" turntable Presto lathes like the 6D or the "The Presto Recorder" that do not have a clutch in the left hand side of the overhead. These screws are not compatible with a crank. You can use them with your 6D with a crank, but you cannot crank a lead in or lead out groove with them.
Screws for these lathes are extremely rare and hard to find.
They are available in 96 lpi or 120 lpi.
I also have a feedscrew endpiece (if yours is missing). For more information, please contact us using the "Contact" button below.