Ultralite 32 Curved Vane Rotor Ultra-Light UL-32 directional vane rotors provide an excellent balance of efficient cooling and lower rotating mass on hard braking dirt tracks or rear axle service on pavement cars. UL rotors are cast from premium grade, long grain carbon iron for long wear, high thermal stability, and resistance to distortion. UL-32 rotors are production machined and well suited to a wide range of sportsman racing categories.