Inside Diameter:38mm Also Fits Many 50cc engine go Kart and Moped 139QMB Motorcycle 38mm Air Filter for Honda Kawasaki Yamaha Pit Bike ATV XR SDG SSR 70 110 125 Dirt Pit Bike 38mm Air Filter for Chinese GY6 50cc QMB139 Moped Scooter Off Road Motorcycle ATV Quad XR50 CRF50 XR CRF 90cc 110cc 125cc Dirt Pit Bike Inside Diameter:38mm Motorcycle Air Filter: This 38mm motorcycle air filter for 50cc dirt bike boost engine horse power significantly, increase engine power and torque outpout. The air filter prevents abrasive particulate matter from entering the engine’s cylinders to ultimately increase horsepower and improve the gas mileage 38mm Air Filter: This 38mm motorcycle air filter fit for 49cc 50cc 70cc 90cc 110cc 125cc 150cc 200cc ATV Quad Dirt Pit Bike Gy6 Scooter Go Kart, etc. It can also improve the look of the engine bay and improve the sound of the of the induction Turbofan Design & High Quality: This 38mm