Traxxas 5381X Differential Spool The number one selling name ins RTR Innovative design and engineering Made using only the highest quality components Use Traxxas stock and hop-up replacement parts to get the most out of you Traxxas RTR vehicles This product is made from high quality materials, and designed for lasting performance This is for use on RC vehicles such as the Traxxas Revo, consult your user's manual for exact parts listings