The Osborn Dronco 4.5" (115mm) ones I have use the standard 7/8" (22.23mm) angle grinder mounting and are rated at 11,000 RPM max so suitable for use on my 4.5" Bosch grinder. The only minor issue I find is due to the depth of the fleece when new it makes it harder to get the pin spanner on the nut but I can live with that. The Dronco part number is 6700 001 100. None of the other discs of this type I've seen advertised had a max speed anywhere near 11k RPM so would have been unsafe in use.