Sait Aluminum A46N are United Abrasives grinding wheels providing quick action on aluminum & non-ferrous metals and claim to outlast the competition by as much as 40%.  They are made of aluminum oxide, a medium grain size and a soft bond for aggressive stock removal without loading.   Applications:  Non-Ferrous Metals such as aluminum, copper and brass.  4 1/2" diameter, 1/4" thick, Type 27 (depressed center), 7/8" bore, no hub.  For right angle grinders.