Air filter and pre-filter inserts, foam (high-volume) (3) (pre-oiled, assembled) (TRX 2.5, 2.5R, 3.3) Use Traxxas stock and hop-up replacement parts to get the most out of your Traxxas RTR vehicles. This product is made from high quality materials and designed for long-lasting performance. This is replacement hardware for use on Traxxas vehicles; consult your user's manual for exact parts listings.