3keego Annular Cutters are best use to drill holes on thick metal materials and large diameter of holes. Mainly composed of two types, High Speed Steel Annular Cutter (HSS) and Tungsten Carbide Tipped Annular Cutter (TCT). 3keego HCR Titanium Coated Type annular cutter can drill holes on hard materials like railway, excavator bucket, or even military tanks. Diameter range from 12mm up to 150mm and more if required.