A retainer ring with four anti-rotational tabs is positioned inside the carbon seal housing and onto the carbon segments preventing the segments from rotating. A lock ring secures the retaining ring and carbon segments. Twenty-four bolt holes secure the seal to the rear air seal. The bolt holes are spaced in segments of six with four bolt holes per segment. The seals 12 o'clock position is marked with the word "TOP" or the irregular bolt pattern can be use to determine "TOP" for you.