Philip, I'm glad to hear they've given good results. Cookson aren't always the cheapest place to buy products, but the price of the 3M radial discs is reasonably competitive, I think. You can get a bit of a discount (I think it's 15%) on tools from Cookson for being a member of the Guild of Jewellery Designers, membership of which is open to anyone.
Ian, yes, there are certainly a few errors in the descriptions on the Cookson site, and I've done my bit over the years to correct some of them. On a positive note, whenever I've had a problem with a defective item from them or any problem with my order, their customer service has always been exceptionally good. In a former life Cookson were known by a name that is probably quite familiar to many of this forum's older members: Johnson Matthey.