45mm Universal fit "Bullet" Air Filter - Motorcycle Scooter Pocket Bike - Red (Model 10403-01) New Performance Air Filter 45mm for Scooters, Motorcycles, ATVs, Pocket Bikes High Air Flow with Excellent Filtration Materials. Added Value: Comes with Clamp, Easy to Install and Maintain. Fits 45mm Carburetor Opening (+- 1mm) (Intake Side) Pliable flanges absorb vibration and can be stretched up to 1/16 In. to fit in-between sizes.