I have a used Standard straight knife for the McNaughton coring system. This is the narrower blade and will fit the early holder head or the newer. As far as I know there are only two blade holders, someone can let me know if that is not correct. Not much of the cutter has been ground away, still lots of use left. Looks like new ones are in the low to mid $70's range. How about $45 including shipping to the US.