Brand New 40 mm HIGH PERFORMANCE AIR FILTER CONDITION: Brand New It may fit XR50 and most china clone pit bikes. This foam air filter has a 40 MM hole center diameter. Flange size is about 53MM.From top to bottom is about 80MM. It's detachable and washable. Get this new filter and it will allow your bike to do deep breath and generate much more power. Adjustable clamp is included