This is for the adapter only.
It will fit a Shars chuck, (we will include the part number, $112 including chuck, taxes & shipping) We will ship this for free also. Chuck is used to holding the valve to polish the stem, with the “thru-hole” rocker arm shafts can be held easily for polishing also. We have also used it on our larger lathe to hold very small items that did not need close tolerances.
If you are interested in the adapter with the 1/2 arbor, contact us for pricing.