All rebuildable motorbike front forks & rear shock absorbers need some basic shared parts - fasteners like locknuts to hold damping pistons to base towers, teflon lined shaft collars or acetal rod bushes to hold sliding tubes concentric without friction, mid-speed valve (or refill / non-return) springs to help tune your shim stack, rubber o-rings to keep oil & gas pressure sealed. These suspension components can be used on either end of the bike when you are servicing or tuning.

These fork o-rings are listed in their categories separately too; there are obvious ones like Top Cap O-Rings & the fluid separating Free Piston O-Rings or the main Compression Piston O-Rings, but you may not have thought of the tiny ones on fork cap Air Bleed Screws. There's small o-rings inside Cartridge Seal Cases as well as Cartridge Rod Oil Locks, plus you'll find big ones sealing between tube legs & Axle Feet with little ones for the Rebound Adjuster too.