Bimetallic hole saw (the original word "according to" is wrong): Refers to a special circular saw for cutting circular holes in modern industry or engineering. It is simple and flexible in operation, convenient to carry, safe, and has a wide range of uses. Installed on an ordinary electric drill, it can easily cut round holes, square holes, triangle holes, straight lines and curves on any curved surfaces such as thin iron sheets, wood boards, plastic boards and other various plates.