PolyMatrix "A" represents the racing brake industry's ultimate achievements in friction material for severe duty, extended high temperature braking. Originally developed for tracks such as Martinsville or Watkins Glen, this phenomenal material provides the highest friction torque values and will outlast all other brake pads. "A" compound comes on smooth under light or heavy braking. It provides excellent cold friction for qualifying and restarts after long caution periods. As rotor temperatures increase, friction continues to rise with smooth engagement and fade-free performance over the full range. This gives the driver never-felt-before confidence to drive deeper into the corners, without the worry of upsetting the car. And, even under the harshest conditions "A" Compound has the strength and durability to go the distance. "A" compound is a superb material on both cast iron and high strength steel alloy racing rotors. It reaches peak performance after one high temperature bedding cycle. Once bedded, it provides a consistently smooth transfer layer during sustained high temperature runs, and eliminates any engagement pulsing or chatter that can result from uneven material build up on the rotor faces. a smooth transfer layer also provides quick, predictable release for maximum consistency. The uniform thermal transfer characteristics of all PolyMatrix compounds will minimize hot spotting and heat checking. Rotor life is ultimately extended over other hard or abrasive brake pad compounds. Wilwood PolyMatrix 'A'' Compound Characteristics: Ultimate high friction compound with aggressive initial response. Long wear rate for severe duty, sustained high temperature braking. Immediate low temperature response for qualifying laps, restarts, and any other applications requiring high response at low temperatures. Compatible with iron, steel, and titanium rotors Applications: Race ONLY compound used in ARCA, ASA, ALMS, Grand-AM, NASCAR, REMAX, SCCA, USAC, and other severe duty oval, road course, and off-road series that require an aggressive response and durability in the highest temperature ranges. Lightweight sprints and club sport racers using steel plate rotors that require fast response at low temperatures with resistance to fade during periodic or temporary high temperature spikes.Pit Stop USA offers Wilwood Polymatrix "A" Compound Brake Pads - Fits GM III Calipers 15A-5737K at low everyday prices. Be sure to check out all of our products from Wilwood Engineering including Wilwood Engineering GM Pads (D52).