RACE/TRACK COMPOUND Designed specifically for heavy duty motorsports, the Porterfield R-4 brake pad was our first and is our original Carbon Kevlar brake pad. Being able to maintain an average of a .50friction level within a very wide temperature range gives the R-4 pad astounding versatility and makes it very suitable for a wide array of various track conditions.With use of the latest ceramic technology, the Carbon based semi-metallic R-4 materials allow the pads to absorb tremendous amounts of heat and dissipate it at a very even rate, while at the same time insulating excessive heat from calipers. Another inherent characteristic of our carbon kevlar material is how quickly the pads warm up to race temperature which is quite helpful during restarts, and when track time is limited. Optimum R-4 operating temperatures are 450ºF and above. When used with cast iron and steel alloy rotors, the R-4 compound requires minimal bed-in period. Throughout the entire heat range, the Carbon Kevlar material will give extremely consistent modulation and predictability smooth release characteristics up to thresh-old. Another benefit of our R-4 compound is that even with the high friction levels and broad temperature ranges, the unique properties of our compound allows the rotors life to be extended to the maximum. This is truly the most rotor friendly racing brake pad material ever. Road courses, oval track, rally, vintage racing,autocross, club events or professional racing events. Tested and raced in countless types of competition vehicles, the R-4 compound from the outset has established its reputation as a Championship winning brake pad material. Set of 4 Pieces Rear for JAGUAR: 2014-17 F-TYPE R, V8S, 2016-17 V6S Equipped with 376MM Rear Rotors Rear for JAGUAR:XJ/XJL V8 V6 OWNERS PLEASE MEASURE YOUR REAR ROTORS TO CONFIRM YOU HAVE 376MM, NOT 325MM (AP1752) NOT FOR USE WITH CERAMIC ROTORS