It is Drill Bits/3-Edge Engraving Bits/Milling Cutter/End Mill/CNC Router Bits. Product Type: 3 cutting edges pyramid engraving bits. Shape: trigonous shape. Material: solid carbide. Application: It is designed mainly for the rotary engraving and marking of Copper, Aluminum, Jade, Redwood, Hardwood, Acrylic, Color Plates, PVC, MDF and PCB etc.