Features: M42 is used as the material. The product is welded by electron- beam and then quenched by vacuum high temperature. Suit for wood,gypsum board,PVC board,aluminum, steel, casting, plastic, stainless steel and other opening operations. After used,please smear some anti-rust oil on the face,to help keep from autoxidation. When using the tapper, please be sure to properly grasp, select, compare and use the tachometer, and constantly add the coolant to prevent the edge- from cracking-. If using the high-speed gun- drill, the switch should be controlled during operation, so as to reduce its speed as much as possible when opening and closing, and it is widely used for tapping on various electric drills of the bench- drill machine. If the perforated iron plate is more than 5mm, cut about 1mm deep first, and then drill through a hole along the saw seam- with a positioning drill, which is more convenient for removing iron chips. Specifications: Product Name: Bimetal Material: M42 Bi-metal Specifications: 32mm 38mm 44mm 54mm Color: Yellow/Black/Red/Gray Suit for wood,gypsum board,PVC board,aluminum, steel, casting, plastic, stainless steel and other opening operations Package Includes: 1 Set Hole Saw Drill Bit Set note: Please allow 0-1cm error due to manual measurement. pls make sure you do not mind before you bid. Due to the difference between different monitors, the picture may not reflect the actual color of the item. Thank you.