C.K T3121 SDS Masonry Drill Bit Set of 7. Carl Kammerling (CK) provides a wide range of hand tools, tool storage, power tool accessories, and security products suitable for professional, industrial, and consumer use. With over 100 years of experience, it is a name known for quality and reliability. The CK T3121 is an SDS concrete bit set containing seven drill bits of varying sizes. The forged steel products are tungsten carbide tipped for durability, while their optimized geometry allows fast and accurate drilling of concrete, stone, and brick. The drill bit sizes included are: 5x110mm, 6x110mm, 8x110mm, 6x150mm, 8x150mm, 10x150mm, and 12x150mm.