This is an optional Kyosho Front Lower Suspension Arm Set in Hard compound. These arms compliment the optional Hard rear arms offered by Kyosho (KYOIF423H) and offer additional stiffness and reduced flex in high heat conditions. Not recommended for low temperature applications (below 70°F or 20°C). Must be used with the optional Kyosho Outer Hinge Pin Set (KYOIFW458).