Features: – Products using 50# steel manufacturing, serrated high-frequency quenching, long life, tooth hardness HRC4-48, the working depth of 25mm. – Nice hole saw kit for drilling round holes easily and quickly. – Sharp and durable teeth of hole saw ensure a powerful and high efficient action. – Suitable for cutting wood, thin sheet metal and thin alloys, gypsum board. – After the use of a small amount of anti-rust oil on the surface of the hole saw bit to avoid natural oxidation, can improve its service life.