You could go to the
Hagon site and find out for yourself but just in case you find that a bit tiresome a summary below - I'm sure you can work out the difference.
Road Shock - Standard Chrome Spring, Black painted 28mm sealed damper unit with standard chrome spring (SA), 3 position spring pre-load adjustment by enclosed cam. Supplied as complete pair with mounting bushes and spring adjusting C spanner. 2-year guarantee.
Custom Shock - Standard Chrome Spring, Polished stainless steel 28mm sealed damper unit with standard chrome spring (SA), 3 position spring pre-load adjustment by enclosed cam. Supplied as complete pair with mounting bushes and spring adjusting C spanner. 2-year guarantee.
Type 2810 Adjustable Shock, Black painted 28mm sealed damper unit with standard chrome spring(SA). Featuring 10 position damping adjustment with automatic compression / rebound balance, 3 position spring pre-load adjustment by enclosed cam. Supplied as complete pair with mounting bushes and spring adjusting C spanner. These units are designed to be fitted with the damping adjuster at the bottom. 2 year guarantee.
Nitro Stainless Steel Shocks. Stainless steel 38mm damper unit fully re-buildable, 18mm piston rod, 10 position damping adjustment with automatic compression / rebound balance. 73mm outside diameter stainless steel spring, choice of colours for alloy parts. Fully progressive spring pre-load adjustment. Supplied as complete pair with end mounting bushes, spring adjusting C spanner and 2.5mm hexagon key. These units are designed to be fitted with the damping adjuster at the bottom. 2-year guarantee.