30 years ago, I would simply have picked up the phone and arranged for a ‘sample’ from:
**LINK**
Rep would have picked one/them up and brought it/them back from Liege on his next trip.🙂
Any size (within reason for a company car), any material and any hardness.
They are still going, but contact lost of course.
Also used very large balls in vertical grinding mills. Up to about 400mm, maybe more. Babcock & Wilcox supplied the coal mill, as I recall…. but they were only about 225-250mm diameter IIRC.
Now, what size were you wanting?🙂