Hub retainer, 17mm hubs, M4 X 0.7 (4) (use with #5853X, #6856X, #6469) 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 users manual for exact parts listings.