Special balls for valves are all those balls that require extra processes to make your valves even more perfect:
90° passage ball
3-way ball with double groove and double milling
Ball with 45° discharge hole
Ball for check-valves
Ball for check-valves
Ball for sprinkler valves
3-way blind balls
4-way special balls
Flow rate regulator balls with double hexagonal broaching
Flow rate regulator ball
Ball with 4 milled ways with planes