I was the plus-7 Set recommended directly by the hotline of Bosch (professional), or by forwarding to a technician there. I asked there for the best original accessories for my GBH 2-28 DFV hammer. With the drills I have now drilled several holes in brick, concrete / aggregate concrete and reinforced concrete. In all materials without effort straight holes driven into stunningly fast time. Sure, a drill is only as good as the machine - but the other way as well! And after I've burned before buying this set on basement shafts two drill in DIY quality and broken I am glad that I have not left this here on heavier work so far down.