Razer wolverine replacement sticks* I'll discuss in the comments but if you're looking for replacement sticks for your RW ultimate controller, a third party Xbox Elite replacement kit works well. Spent £20
Razer Wolverine V2 Chroma Review: New customizable controller for Xbox
Razer Wolverine V2 Chroma Xbox pro controller is a handful of buttons for $150 - CNET
Razer Wolverine Ultimate Review by Adam Dileva - XboxAddict.com