Nursemike, I'm an idiot. I have old cast-iron hot water radiators in my house with 1/4" sillcock vent valves on them (why they can't have something you can get a wrench or normal socket on, I don't know). I've been buying packs of cheap pot metal keys for years that split after a few uses. Not too bad if your last one splits while trying to open the valve, but when you're trying to tighten it... Now I'm going to go out and buy the one you linked to, thanks!