Ohlins Road & Track Coilover System 2000–2006 BMW M3 (E46)The hlins Racing Road & Track suspension gives customers a true racing experience with their own cars, without losing comfort when commuting to work. hlins Racing unique Dual Flow Valve (DFV) technology allows you to quickly change the stiffness of the shock absorber. When arriving at the racetrack, just turn the golden knob clockwise on the damper to set it in race mode this action changes all four areas in the damper; low and high speed compression