Reduce heat transfer from the brake pads to the callipers and brake hydraulic system to lower the operating temperature. When the rotors and pads are hot, heat transfer via the calliper pistons to the callipers and brake fluid may lead to fluid overheat and brake fade. Fluid fade will lead to soft brake pedal and affect modulation, and is dangerous when there is sudden loss of braking power at the track.
Lower long term maintenance cost by protecting the calliper seals, dust boots, and brake fluid. Excessive heat will deteriorate these components a lot faster and lead to unnecessary replacement cost, plus wasted track time. Boiled fluid needs to be replaced after every track day.
OEM FK8 Brembo 4 piston callipers are known for turning brown or even black after track use. This low cost solution can reduce the likelihood of discoloration.