Got the regular (non-HD) 418s since I mainly ride 1-up.
I believe the damping is achieved by an adjustable orifice in the hex adjuster up top. The higher the number, the smaller the orifice. That will control the rate at which oil passes from the high pressure side to low pressure side internally. When the shock compresses under load, the oil pressure tries to equalize through that orifice. Lower numbers allow the oil to equalize faster, reducing the damping.
Cam adjuster on preload is a pain - - and much easier if I just bite the bullet and pull the beetle bags off first. One good thing - - you instantly know which cam the shock is set to. With the stock shocks, I always wondered where to line up the little number.