The processing is, as I am now accustomed wedge, very good, the drills are stable, run all perfectly round, drill and clean with decent feed in every imaginable stone material. In flow, I can recommend to prick a small hole with a center punch or a compass point and initially drilling the leveling with a sharp HSS drills before using the rock drill for the wall underneath! The blow I only switched on when it went without no fuss. Note the slow speeds!