Anything canecreek, I don't think they even list mine of their web site, its awesome, I repacked/cleaned the bearings(it's not cartridge) and now its smoother than when it was new. Personally i' have now prefer loose(well its got retainers) ball headsets over, Cartridge. Cartridges are just not as smooth. Plus my headset cant cost much more than a new set of cartridge bearings for a high end headset.

(its IS-19 or some such)