It's a P-mount equivalent to the 680/681, probably an OEM version. Any of the 681 or 681 styli will work fine in it but, if you're going to use it in a P-mount table, you should probably remove the brush.
Sweet! Thanks for the info! I hope this P mount version is less subject to simblence that its standard mount bretheren. I never could get the 681 to behave.