08-14 Nytro FX/RTX Zero Pro Fox rear shock. Zero Pro Fox shocks are the "Work Horse" of snowmobile shocks. Standard Yamahas use Kayaba shocks that even if rebuildable have very limited parts availability. Nitrogen charged Fox shocks feature adjustable valving, ice scraper technology, velocity sensitive damping, and are 100% rebuildable with parts economically available. Get Zeroed In!