K&N Engineering Universal Oval Tapered Air Filter - Rubber End Cap RU-1820When selecting one of K&Ns universal oval tapered air filters, you should consider the following dimensions as they relate to the specification chart: Mounting Flange Inside Diameter This is the most critical dimension and should be very close to the diameter of the applications inlet flanges. The flanges will stretch up to 1 8in. for those in between sizes. Filter Oval Dimensions This is the length and width of the filter. Always use the largest