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The snap ring snapped when i tried to remove it in the rear wheel. i bought the online manual at cyclepedia and it does not even show a snap ring. only the 1 side had one, what is the reason for it being there? only one side had it, do i need to order a new one? or 2?

EDIT:
Sorry forgot to add it is a 2001 KDX220

What does the fiche show .... only one.

92033: CIRCLIP,42MM Bike Bandit Part #1978-001 $3.64