The RIDGID M114 (52980) 4 1/2 in. (114 mm) Bi-Metal Variable Pitch Hole Saw outperforms and outlasts traditional standard pitch models. It features a bi-metal construction with a cutting edge made from premium M42 high-speed steel. The varying teeth height and gullet sizes result in much faster cutting as well as a longer life. The hole saw is ideal for wood; mild, tool and stainless steels; cast iron; brass; and aluminum.