The FR4 Sport Edition 4-piston brake kit is a competitive brake system developed by Feizi FeccR specifically for small vehicles. Adopting 7075 aviation aluminum integral forging process, it has a piston area of 44.56 cm ². Minimum compatible with 15 inch wheels. The FR4 is also equipped with a quick release pad design and optional titanium alloy pistons, providing powerful braking power for small racing cars.