stem-guided valve & cross-arms seat features an extra wide metal to metal seal on the valve flange. The serrated upper surface on the valve gives a longer non-breathing seal between valve body and insert while the rigid seat cross-arms give greater strength and positive sealing.
The strong, thick, valve knock off nut holds the insert tightly reducing flex and breathing which lessens the chance of foreign matter getting between valve and insert.
Material is 20CrMnMo/20CrMnTi forging steel,carburizing and quenching,thickness is 1.5mm-1.8mm,hardness is HRC 58-62, and hardness of the core is HRC27-33

The 55 angle and screw thread of the valve have