https://www.wvf-valve.com/butterfly-valve/wafer-butterfly-valve/rubber-seated-butterfly-valve.html
Body is made of Cast Iron GG25 or Ductile iron GGG40/GGG50
EPDM, NBR, PTFE liner with reinforced seating area
Shaft made by SS410, SS420 or SS416
Both inner and out part is Fusion-bonded epoxy 300microns minimum