Mirka Galaxy 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 formed, making it possible for the Galaxy to continue cutting longer.