38mm Universal fit "Bullet" Air Filter - Motorcycle Scooter Pocket Bike - Black (Model 10401-04) New Performance Air Filter 38mm for Scooters, Motorcycles, ATVs, Pocket Bikes High Air Flow with Excellent Filtration Materials. Added Value: Comes with Clamp, Easy to Install and Maintain. Designed for 50cc up to 125cc Pliable flanges absorb vibration and can be stretched up to 1/16 In. to fit in-between sizes.