I bought this lock to catch an error (cable routing from oblivion in a concrete pillar) without much hope given the price. And I got my money. I had previously drilled about 800 mm with a wick 8 and then with it and I managed to pass my sleeve. However, careful not to press too top and let it do the perfo, well "UNCLOG" dust regularly. I have since other shallower drill hole, no worries for now.