In moto01: Plastic washers 2,5 kn =) , selens 212 kn piece . I have question about that plastic washers and selens

. The guy in the store gave me the black plastic washers and on my scoot where white (bigger) , but the guy in store told me that the white are from runner. Should i buy for runner ? And selens , how much KM,s they last if you stunt almost every day ?