https://www.wvf-valve.com/other-valves/air-valve/ductile-iron-ggg40-air-valve.html
The body made of ductile iron GGG40
The bolt is made of stainless steel or carbon steel
The ball is made of metal insert fully covered with a rubber layer
All the internal and external cast iron surfaces of the valve are covered with powder epoxy paint
Connection: Threaded or Flanged acc. to BS4504/DIN2532/ISO 7005
Single sphere or Double spheres air valve
Seat material made of PTFE, F46, EFP