Rotary Wide Cone FINE Finishing Grit, drills own pilot hole. Make and enlarge holes. Shaft / arbor 3.1 mm (1/8") Overall length 40mm Gritted length 16.5mm Widest point 16mm (all measurements are approximate) Our Rotaries have an integral arbor,enabling them to be used in reversible drive tools. They allow the user to cut a wide range of materials quickly and cleanly leaving an excellent finish. All rotaries are ideal for routing, shaping and removing materials without tearing or clogging. Use on all Woods, Glass Fibre, Carbon Fibre, PCB, Kevlar, Plexiglas, Lexan, Perspex, Acrylics, Plastics, Polystyrene, Ceramics etc. Excellent on Perspex, Plexiglass, Lexon, use below 10,000 RPM and they will not melt, crack or chip them. (not recommended for use on metal) Note Rotaries should be fully inserted in to the chuck and tightened before using. Maximum RPM 20,000 Low - Medium. SAFETY:- Always wear protective goggles when using Rotary Tools. IMPORTANT:- Carbon Fibre should not be cut using an electric drill, because of the possibility of electrocution.