101 Octane sprocket with 55 teeth for 420 drive chain suitable for Aprilia RX, MX, Explorer Sniper, Generic Trigger, KSR Moto, Keeway and Ride geared mopeds. This sprocket with 55 teeth corresponds to a slightly shorter ratio compared to the original chainring. We recommend using this chainring with 420 chain with 140 links, so that the chain can be shortened to the appropriate level. Mounting hole: 8.5 mm Inside diameter: 105mm Number of Holes: 5 PCD: 120mm standard: 420 offset: no / Teeth: 55