I haven’t checked them myself but KWI says the new 3 arm rollers are harder than the previous rollers, I do notice we are not seeing the roller wear with the 3 arms as bad as the 4 arms.
The tang is the stop for the weights, the 4 arm clutches have a peg for the tip of the weights to bottom out on, the 3 arms do not so the tang at the pivot point is the stop.