Multi-function glass drill bit set, model Multi-functional Glass Drilling, made of tungsten carbide for metal drilling and related metalworking tasks. Drill bits cover sizes from 3 mm to 12 mm (about 0.12 in to 0.47 in) and have lengths in the 80 mm to 120 mm range (about 3.15 in to 4.72 in). Customizable, brand lavie.