This is an optional Team Losi Racing Rear Torque Rod Set, and is intended for use with the Losi TEN-SCTE when equipped with the optional TLR Flex Tuned Lightened Chassis (TLR4000). The Rear Torque Rod controls the amount of rear chassis flex. Constructed of high grade aluminum and hard anodized for superior durability and style to match the look of the Tuned Flex chassis. If you are running the Flex Tuned chassis this is a most have part.