They don't require any calibration or adjustment or anything, the little red doughnut will align itself once you've shifted to the extremes of the cassette (large cog and small cog). Just install it between the shift housing and the shifter and you're all set.
These things are really cool and I wish Campy would engineer something like it for their shifters. Advantage: Shimano
It is my belief that every person in this world has something to teach, and everything to learn.
In memory of Jim Price (aka. sydney) ...