Saw Hole Saw for Core Drill Bit Diameter】55mm Diameter. The core drill bit is made of carbide alloy steel; the blade is extremely sharp and resistant to cutting. 【Bi-Metal Saw Hole Saws】A spiral drill bit inside for faster drilling, which is removable and replaceable. 【Safe Collar】With a built-in safety collar to prevent over-drilling. 【Uses】Can be clamped onto a hand drill and a bench drill for thick sheets of steel, cast iron, stainless steel, non-standard angle iron, and other open metal holes. Carbide Hole Saw Made of high-quality hard alloy, durable. Precision-ground tungsten carbide teeth for long life and a clean cut Fast. Each edge is part of the cutting action, making it difficult for the hole to collapse. Fine Grinding Center Drill Bit The hole saw has a helical drill bit inside, which is removable and replaceable. A smooth cut ensures precise drilling. Carbide Teeth and Core Drill Hole Carbide teeth for quickly cutting round and clean holes. The core drill hole facilitates