100mm wire brushes for a bench grinder do seem a little hard to find.
Maybe Mr Ardvark would be kind enough to give more details of the MM one he recommends, as I was unable to find it on their website.
There are a couple of candidates here:
https://www.wire-brush.co.uk/wirebrushstore/prod_946821-Rotary-Wire-Brush-100mm-Fine-Gauge.html (says made in Germany)
https://tool-wise.com/products/100mm-diameter-crimped-wire-wheels-030-0teel-wire-spec (SIT brand, made in EU)
https://www.rowland-tools.co.uk/pro...ch-grinder-crimped-wire0-2-o-100steel-sit0048 (same SIT brand, but out of stock).
Maybe the OP can look for the SIT one from alternative suppliers.
I wonder if it is possible to buy an adaptor that screws onto the shaft of the bench grinder with the same thread as a 100mm angle grinder. Then 100mm grinder wire brushes could be fitted (but again, 100mm is not a popular angle grinder size).