038-00-057 this is the spirolox retaining ring. Also known as spiral retaining rings, clips, spiral loc, or spiral locks. It holds the BOC piston on the adapter post. It is the same, regardless if you're building a 6-1/2", 8-1/2" or 10" stroke BOC shock.

Fox's bottom-out control provides extra resistance against bottom-outs.

As the shock is compressed, the secondary piston that threads onto your shock shaft above the rebound valving stack will enter the bottom-out cup in the final 25% of travel to produce up to 3000 lbs of additional damping force. This allows the shocks to be tuned to give improved small bump compliance in the upper portion of the stroke, while still maintaining the ability to absorb huge impacts effectively.

Important Notes: