Solid Material: Twist drill bit is made of high quality alloy drill bits and HSS bits for durability and long service life. Uses: Mainly for drilling wood, beads, resin, basswood, ox horn, olive, PVC, walnut, plastic, beeswax, acrylic and other materials; Not suitable for drilling hard materials: stone, iron, steel, glass. Precise: The twist drill bit set comes with 25 different miniature drill bits. Portable and Easy to Use: Pen-sized, easy to carry and store. Just push and drill turns automatically without any use of batteries. The hand twist drill is useful for precision drilling, tool making, model drilling, engraving as a profession or hobby. Accurate, precise and efficient, use for drilling wood, plastic, rubber and many other soft materials. from 0.3mm to 3.6mm for various purposes. Material: Alloy (drill), high speed steel (bits) Color: Black Chuck Clamping Range: 0.3-3.4mm Drill Bits: 0.5mm (50pcs), 0.6mm (50pcs), 1.0mm (30pcs), 1.2mm (20pcs), 1.5mm (20pcs), 1.8mm (20pcs),