i think its element that has that knob. the guy charges like 65 bucks for em they come from sweden so his english sucks. they use a set screw to keep em in place which sucks though. and u gotta tap a 12v source for it to light up
You have to ask him to custom make it. Yes it uses set screws, but I have had it for almost a year and a half, and I have had no issues with it coming loose.