I bought a budget one off the bay a few years back and been pleasantly surprised, I'm sure it was silverline, came with various adapters for different shaft diameters.
I had a 8" silverline one that was ok then I got one off eBay from China and it was terrible. The wires were in big bunches one side and very thin the other so it vibrated like a sumbitch. Normally they come with a pile of adapters but I also had to use a spacer on mine.
P.S. never use without specs, and if you can make an apron out of something because they throw wires off like darts esecially when new.
I use one of those on a hero-sized 7" grinder with a home made adapter. Awesome tool but you have to command it well so it doesn't eat your body parts.