Suspension arms, rear (left), heavy duty, adjustable wheelbase (upper (1)/ lower (1)) Tra8634Details: Heavy duty E Revo suspension arms utilize our latest proprietary composite material for extreme durability. Traxxas designed this composite specifically for high loads and hard landings with just the right amount of flex to resist breakingeven in cold weather. Whether youre sending it at the skate park, or launching off a ramp, these arms are built for extreme punishment.