DURABLE CONSTRUCTION: Crafted from heat-treated carbon steel for exceptional strength and durability, ensuring long-lasting performance even under demanding drilling tasks. MULTIPLE DRILL BIT TYPES: Includes twist bits, spade bits, and masonry bits, offering versatility to handle a wide range of drilling needs. SECURE AND PRECISE: 1/4" hex shank design provides a secure grip and reduces slipping or wobbling during drilling, ensuring accurate and clean bore holes. PRECISE BORE DIAMETERS: The Cheston Power Drill Bit Bore Set includes three essential sizes: 12mm, 16mm, and 19mm. These specific bore diameters cater to a wide range of drilling requirements, providing you with precise and accurate results.