This NCY adjustable secondary sliding sheave has two sets of ramp angles,
one steeper than the other.
These allow you to adjust how quickly the pulley engages. A quicker engagement means more power off the line, and more gradual engagement gives you more power at speed.
This is a major performance improvement!
(using genuine yamaha parts is over $300 and does not have the performance)
In the clutch diagram, this replaces parts numbered:
5 ,6, 7, 8, 9, 10, 11, & 15