Features and functions of each part; Product Name: NANIWA Pro Cutter Concret; Model: DO-4001; Dimensions: Outer Diameter 4.1 inches (105 mm) x Thickness 0.08 inches (2.2 mm) x Hole Diameter 0.8 inches (20 mm); Electric Tools: Circular Saw / Gisque Grinder Precautions for Installation: Use with flange that matches the center hole diameter without any rattling or shakes. Lightly cut and refill. Please blend... Do not cut it too much while cutting, do not give it too much forceful... Avoid cutting diagonally (it may cause side pressure on the blade); Avoid cutting metal (dull sharpness and shorten life); Can be used with dry type, but if you use it with water it will improve sharpness... If the sharpness is reduced, please use a soft grindstone or red brick for safety. Safety. Please be sure to put it on. Please be sure to use surface protectors; Do not cut curves.