F = INSIDE FLANGE DIAMETER: This is the most critical dimension and should be very close to the diameter of the application inlet flange. The K & N filter will stretch about 1/8’’ for those odd sizes
FL = FLANGE LENGTH AND ANGLE: If no length is listed it will approximate 5/8’’ long. The angle is listed in degrees and helps to position the filter when space is a problem
D = DIAMETER: This is the overall diameter of the filter. Always use the largest diameter practicable to insure maximum filtration
L = LENGTH: This dimension does not include the flange length only the body. Always use the longest filter practicable for maximum filtration
O = OFFSET: Sometimes the flange is offset to one edge of the filter
