Screw stainless steel.
Ball stainless steel, POM or ceramic Si₃N₄.

Ball-end thrust screws with full ball are used when a clean, polished contact surface is required. Longer versions have been designed especially to be glued in, allowing mechanical connecting elements with external threads to be made cost-effectively for small and medium-sized runs. Silicon nitride (Si₃N₄) is characterised by a combination of excellent properties, these include high resilience and strength, excellent wear resistance and good chemical resistance.