Lightweight magnesium Rok Shifter engine mount, half the weight of the aluminum equivalent. 5mm lower than the OEM mount to lower overall center of gravity. Fits 30-32mm frame diameter and 90-92mm frame spacing. Includes frame specific clamps. Select 90mm for CRG made karts (CRG, GP, Aluminos, CKR, DR, Zanardi, Maranello, etc.). 92mm for most others. Approximately 650g weight, 8oz weight savings!