StopTech Sport Rotors are premium quality replacement brake rotors that feature a signature "short slot" design. The slot improves brake system performance by wiping away the debris of used friction material that otherwise accumulates between the rotor and pad. This keeps fresh pad material exposed to the rotor surface and helps prevent pad glazing. The edges sweeping the pad slightly increase the effective coefficient of friction or "bite," amplifying brake system response to pedal input. By providing an escape path for water, slotted rotors can also improve initial brake response under wet conditions. Premium e-coated rotor with advanced metallurgy that greatly reduces pad squeal. Especially effective with higher friction, European style brake pad compounds. Added Molybdenum and Chromium to resist rotor cracking 2008 - 2011 Audi S5; 2010 - 2012 Audi S4