Renthal 2240-520-50GPOR Twinring Orange 50-Tooth Chain Wheel Fits all KTM 125cc-620cc 1999-2011 off-road motorcycles running 520 size chains The longest lasting most durable off-road sprocket you can buy developed over 5 years Inner ring is made from high strength, ultra light 7075 T6 aluminum for weight savings; outer ring is made from electroless nickel coated steel for extremely long wear life Outer is expanded at 200 degrees centigrade and then fitted to inner, creating a permanent bond for the life of the sprocket The unique flat face design keeps weight to a minimum and means the Twinring's as narrow as a regular chain wheel; self-cleaning mud grooves between every tooth on both sides prevent dirt build up