Designed specifically for heavy-duty motorsports. The carbon based semi-metallic R-4 materials allow the pad to absorb tremendous amounts of heat and dissipate it at very even rate. Carbon Kevlar material warms up to race temperature quickly, which is quite helpful during restarts, and when track time is limited. 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 predictably.
This is truly the most rotor friendly racing brake pad material ever. Good for road courses, oval track, rally, vintage racing, autocross, club events or professional racing events.
 

R4-E Endurance Race Compound
A carbon kevlar compound made to last a bit longer than the original R-4 compound.
The R4-E compound is designed to endure higher prolonged temperature and still has pad life as long or longer than Porterfield R-4 do. This pad is great for club enduro events and applications where temperatures are at their maximum.

R4-1 Vintage Full Race Compound
Developed using knowledge testing in the vintage racing community. Optimum uses for the R4-1, under conditions where very high friction is needed with minimal warm up time and in applications where there is difficulty in maintaining sufficient heat with conventional race pad compounds. Widely used on vintage GT and formula cars the R4-1 is also gaining popularity in off-road and rally-cross classes. Great modulation, consistent pedal feedback and rotor friendly at all temperatures as with all the other Porterfield Carbon Kevlar compounds.