Honda pit dirt bike XR50 CRF50 XR SYM Kymco Yamaha PGO MBK 50 Air Filter 35mm 1.Increase airflow 2.Adds up 2 to10 horsepower depending on your adjustment. 3.Universal conical filter and clamp 4.Strong - pliable rubber flanges 5.Inside Inside Diameter : 35 mm , Overall Height: 2 3/4" , Outside Diameter at Widest Point: 2 1/2" , Outside Diameter at Top: 2"