Camel CGW brand 4 1/2" diameter grinding wheels A24N have a soft bond construction for fast stock removal.  They are made of Aluminum Oxide grain and have a depressed center (Type 27).   1/4" thickness and a 5/8" arbor with hub.  Grain Size:  Course   Grade:  Medium.  Applications:  ferrous metals such as iron, steel, welds, etc. and low grade stainless steel.  For angle grinders.