DeWALT DW5242 Percussion Bit Hammer Drill Bit, Spiral Flute, 7 in L Flute, Flat Shank, 1/2 in Dia Shank          Power through masonry, concrete, rock and more with DeWALTA(R) hammer drill bits. Featuring rock carbide tips that maximize surface contact for extended bit life and a 4-flute design that cleans debris while you work. Three flats on the shank eliminate bit slippage.