Barnett Scorpion Billet Lock-Up clutches progressively increase pressure as RPM's increase. Easily adjustable by adding or subtracting weights on the 6 pressure arms. Barnett claims these are the ultimate in performance for your American V-Twin. Whether your bike is stock or modified- street or strip- the Scorpion has what it takes to get the job done and look good doing it. These Scorpion Billet Clutches feature a 100% or more increase in clutch surface area (compared to stock) and include a CNC machined billet aluminum pressure plate, friction plates, steel plates, a steel inner hub, and additional sets of coil springs to allow you to tune your clutch to your needs. The Scorpion can be run dry in an open belt drive or wet in a closed primary.