Faithfull Screwsink Set 4 Pieces is manufactured from steel material making it robust and strong. It is used for drilling, countersinking and counter boring in one operation. This product is used in most hand or power drills. The countersinking part can be slid up and down the drill part of the tool by means of a hexagon key. The product is used in all trades including joinery, electrical and plumbing. This pack includes pilot drills with sizes 6 (7mm), 8 (8mm), 10 (10mm) and 12 (11.5mm).