TREK FX Series 7.9 7.7 7.5 7.5 5.3 7.2 7.2 - Rear Derailleur Mech Hanger CC013
(a) Your existing hanger, back and front, preferably having removed from your bike & rear derailleur, OR. Bontrager is owned by Trek as well and that's why you will very often see Bontrager parts on Gary Fisher, Trek and Klein mountain bikes.