BLOX Racing high compression standard size valves are forged from EV8 stainless steel. Each valve then undergoes a heat treatment process to increase strength then coated using black nitride to provide superior wear resistance and minimize power-robbing friction. Black nitride provides the valve head with superior protection against wear and corrosion and greatly reduces the amount of friction between the valve stem and guide. The less friction produced the more power gained! BLOX Racing valves are specially designed to increase intake and exhaust airflow through the cylinder head. BLOX Racing valves are specially designed to increase intake and exhaust airflow through the cylinder heard. BLOX Racing valves increase compression by approximately 0.3 points. For best results, use with BLOX Racing valve springs and Ti retainers. Set includes 8 x intake valves. Specs Head Diam: 31.00mm (std) Stem Diam: 6.57mm Length: 105.40mm Material: Black Nitrided Valve Type: Intake Engine Applications B18A/B B20B