Various sizes: Hole saw diameter: 55 mm. Pilot drill bit length: 110 mm. Wide applications: Widely used for drilling clay walls, foam walls, brick walls, and concrete walls, or for installing pipes, water pipes, and drain pipes. Packaging: Each hole saw is individually packaged in a plastic box, and each bit is also oiled to prevent rust. High quality: The hole saws are made of high-quality tungsten carbide, which is sturdy, durable, and wear-resistant. The pilot drill uses YG8 and YG11 materials, which have high hardness, rust resistance, and strength. Smooth cutting: The external groove of the concrete hole saw ensures a smooth and clean cut of the hole saw blade, making the hole more precise, which ensures superior performance.