DESCRIPTION: Medium Tough Case System Set Connectable Case allows multiple sets to be stacked and locked together. Extreme Masonry drill bits have a hardened steel body and core reinforcement for maximum strength combined with high drilling speeds in concrete and masonry. Anti-slip shank – 3 milled clamping surfaces prevent rotation of the drill bit in the chuck. Masonry drill bits are typically used for drilling anchor, plastic plug, fixing and pipework clearance holes. Metal drill bits are made from high speed steel for wear resistance and longer life.