These are very good concrete drill. After 100 holes in harder concrete with the 5-er the drill was still in good condition. For these holes I would have probably consumed more Cheap drills. There is the 5 star. Out of curiosity (because there are several negative reviews, not only here but also in testberichte.de) I have done well drilling tests in gray granite. Again, the result was very good for me. Quite strange, the quality is there not always the same?