6PCS in a set: Shank diameter: 8mm; Cutting edge diameter: 18mm 20mm 22mm 25mm 30mm 32mm. Made of tungsten carbide steel, this bottom cleaning bur has high hardness and long service life. Excellent Design: double-edged cutting design, excellent concentricity, higher efficiency. Usage: Can be used on the following materials: wood, acrylic, MDF, PVC, 3D engraving, chamfer, etc. Suitable For: Electric trimmer, milling machine, bakelite engraving and milling machine, CNC engraving machine, CNC machining centers and other machining tools. Material: Carbide Tipped Stem diameter: 8mm Cutting diameter: 18 mm Cut height: 13mm Total length: 45mm Material: Carbide Tipped Stem diameter: 8mm Cutting diameter: 20 mm Cut height: 13.5mm Total length: 45mm Material: Carbide Tipped Stem diameter: 8mm Cutting diameter: 22 mm Cut height: 13mm Total length: 45mm Material: Carbide Tipped Stem diameter: 8mm Cutting diameter: 25 mm Cut height: 13mm Total length: 45mm Material: Carbide Tipped Stem diameter: 8mm Cutting diameter: 30 mm Cut height: 16mm Total length: 48mm Material: Carbide Tipped Stem diameter: 8mm Cutting diameter: 32 mm Cut height: 16mm Total length: 47.5mm