Manley valves have set the standard for excellence in quality, material and design in the performance world for four decades. Manufactured from proven Race Master materials, Manley valves feature chrome stems, hard tips, fully machined surfaces and swirl polished radii. Many applications are Pro Flow design for maximum air flow. For 3V engines, XtremeAlloy exhaust material comes standard.NOTE: THESE VALVES ARE SOLD EACH SO YOU MUST ORDER THE QUANTITY YOU NEED ( DOHC ENGINES USE 16 VALVES ON INTAKE AND 16 VALVES ON EXHAUST ). Intake valves are sold separately.