It allows for an easier pull on a Harley hydraulic actuated clutch... It also moves the engagement point closer to the bars like my cable clutches.
I have a 124" engine that puts out 136HP & 151TQ. I went to a Barnett Heavy Duty Spring and AIM VPC to hold the power. That made the clutch pull much stiffer than OEM. It was a pain in the hand, during slow bumper to bumper traffic. The high clutch effort was exacerbated by the engagement point of the Harley hydraulic clutches which is towards the end of the lever travel. This engagement point is NOT adjustable like on cable clutches.
So far, this slave cylinder is doing what I needed. It is also a simpler install than its competition, by AIM. The AIM kit requires a secondary slave cylinder AND master cylinder change, at a higher price point