The ServoCity 8mm Pitch Press-Fit Pinion Sprocket (8mm REX™ Bore, 8 Tooth) - 2 Pack is designed to drive an 8mm pitch chain efficiently. It securely press-fits onto an 8mm REX™ shaft, eliminating the need for axial constraints in most applications. Integrated shims allow for seamless placement against bearings without causing binding. Constructed from acetal plastic, this sprocket offers low friction and excellent wear resistance.