The IDEAL Electrical 36502 Electrician's Bi-Metal Hole Saw Kit, 19 Pieces is optimized for cutting a wide range of materials. This model is constructed out of M42 high speed steel with 8% premium cobalt content, resulting in high strength and greater wear resistance. Solid steel backing plate means no need for drive plate. The unique fleam ground teeth design results in improved performance and efficient chip removal. The wide diamond eyes aid in easy plug removal. The 36-502's 4/6 variable pitch geometry cuts down on harmonic noise to minimize tooth strippage.