The Disston Blu-Mol BI-Metal + Cobalt Holesaw - 121mm is manufactured from M42 Cobalt BI Metal and provides up to 24% longer life vs standard non-Colbalt Holesaws. It features a 5mm heavy duty backing plate for durability and a 48mm depth of cut which is ideal for thicker materials. The 4/6 variable pitch produce a cut that is 30% faster, and the oversized holes create a vacuum when cutting which removes dust from the cutting area and helps to keep the cut cool, prolonging the life of the tool. Many users of Holesaws spend longer trying to remove the plug (cut material) from inside the Holesaw than they do making the required cut. The oversized diamond shaped holes in the wall prevent this issue and ensure quick and easy plug removal. The “Cat’s eye” holes in the backing plate (larger sizes only), add another option for plug removal, increasing the above-mentioned vacuum effect and provide clear visibility through the back of the Holesaw, ensuring an accurate cut.