Mirka Galaxy Sanding Discs 150mm/6", 100/Pack P120Mirka Galaxy is a new kind of high technology abrasive. It combines effectiveness with long use life, thanks to a new kind of self sharpening ceramic grain, a clogging resistant coating and the new Multifit hole configuration. How do you keep an abrasive sharp? Make it re generating. The ceramic grains used in the Mirka Galaxy are self sharpening. This means every time an edge of an abrasive grain breaks off, a new cutting edge is simply formed,