heavy duty carbon steel shade: made of heavy duty carbon steel with nickel plated finish for extreme hardness and longer life, it resists wear, corrosion and frequent use without breaking. hss circular saw blade: the circular saw blade is made of high speed steel (hss), sturdy and sharp enough to maximize cutting speed and achieve perfect results. versatile and efficient: the mini cutting discs are suitable for most electric drills and are very easy to install and replace. the corresponding 1/4" hex shank makes it powerful and perfect for pvc pipes, plastic pipes and wood. it can also be used to cut soft metal pipes, but use coolant or water when cutting soft metal pipes to prevent the circular saw blade from overheating. installation steps: ext. bar. - sawtooth washer - blade - flat washer - screw. tighten the screws. oil film protects the blade. once set, connect it to a drill and start using it. note: for your safety, please wear gloves and glasses and pay attention to the spark when using disc drill blades. the maximum speed of the saw blade should not exceed 20,000 rpm. if you have any questions about the product, please feel free to contact us and our customer service will help you quickly.