Different sizes: hole saw diameter: 55 mm. Pilot drill length: 110mm. Wide application: widely used for drilling clay walls, foam walls, brick walls and concrete walls or installing pipes, conduits water and exhaust pipes. Packaging: Each hole cutter is individually packed in a plastic box and each bit is also oiled to prevent rusting. High Quality: Hole saws are made of high quality tungsten carbide, they are sturdy, durable and wear-resistant. The pilot drill bit uses YG8 and YG11 as material because it has high hardness, rust resistance and sturdiness. Smooth cutting: The outer groove of the cement hole saw ensures smooth and clean cutting of the hole saw blade, making the hole more precise, which provides superior performance.