its the brass one that has a stainless steel screw in it. it is the duel ball bearing kind. its for and underhood instalation. go to www.gotboost.us and you can see pics and how it works.
i have heard about those, only good things, get rid of turbo spike etc etc, the one you want is the Vspec Greedy II profec controller, ebay has them for $284.00 look around you may get a deal..