Stainless steel and anodized aluminium.
Look after your fork seals with fork bleeders reducing air build up in your forks
Keeping the air pressure neutral in your forks also helps keep your spring rate correct, if you gain air pressure in your forks it acts as an air spring, it also alters your compression and rebound settings.
For technical riding, this can push your front tyre offline losing traction at the wrong time, it can also make your suspension rebound too fast making the bike bouncy.
M5 X 0.8