(f) Internal diameter of the assembly entrance: this one is the most important dimension and must be very near the diameter of the entrance of the application. The entrance adjusts until 1/16 " for the intermediate sizes.
(MA/SA) Dimensions of oval filter: one talks about to the length and the width of the filter. Practitioner always uses the longest filter sufficiently to adjust to the application.
(l) Length of the filter: this dimension is the length of the body of the filter solely, does not include the length of the entrance. Practitioner always uses the longest filter sufficiently to obtain the maximum filtrate.
(FA/FL) Angle or length of the entrance: if it does not appear an angle listed in the table of specifications, the entrance is straight. The listed angles are in degrees and they are possible to be used when a space problem exists.
(FO) Off-center entrance: in some cases, the center of the opening of the entrance is outside the center of the base of the filter to allow a better adjustment.
PreCharger: a PreCharger K&N is a package filter designed especially to prolong the time on watch of a filter K&N used in conditions where there is too much dust. There are them available in blue, red and yellow.