It's a Scotts steering damper very trick cost around $350 I think. They are a little more difficult to mount then the typical piston type. In theory I haven't used one they have both adjustable low speed and high speed damping. You really only want high speed damping to stop violent shaking. The low speed just interferes with steering effort and the bikes natural tendency to self center. The problem with the mounting is that to do it right you need a custom made top triple like the one I made below.
I bought the entire kit for about 400.00 on ebay. And the damper is made by ohlins, exactly the same as a scotts. They are all over ebay. But the mount only works for models to 01. It's nice to see someone is looking at my posted pics.