Question
Does the 50mm refer to the top diameter and what size filter paper should I use?
Answer
Yes, FUG-450-050 is approx. 50mm diameter at the top.The inner plate is approx. 15mm diameter but the perforated area where the holes are is only 6mm across, so you would need to use something like 10mm diameter filter paper.
We do not supply filter paper this small, but you could cut your own out of larger filter paper sheets using no. 6 to no. 8 cork borers.