The one I originally bought and worked for FX valves had a 1/8" pin. But it seems like they are asking stupid money for them right now - over $40.
Maybe a year ago I went with the Saber Tactical bottle degasser kit, and never looked back. It seemed expensive at the time, but with all the use it has had, it now seems to be bargain priced. And priced at $25 over a simple pin spanner from Amazon, there would be no question that I'd pop for the ST kit if I needed something today.