Hmm... I'm not sure I know what you're on about... :?
It's just a steerer tube extender. It goes inside the too short steerer tube and because it works just like the old quill type system it wedges itself in there as fine and tight as you like. To be used with an aheadset system which I'm guessing is the case here as we're talking about Rockshox Psylo's?
All I can say is that it works just fine, a friend of mine has got one fitted to his forks, no issues at all.