Screwdriver bits are typically made up of a shaft and a tip. A screwdriver bit's shaft is typically hexagonal in shape, with six flat sides. This shaft is fitted into the end of a screwdriver that has a bit holder. The shaft's shape prevents the bit from rotating within the bit holder. The tip end of a screwdriver bit may have many shapes.The bit's head is designed to fit into the head of a screw. As the screwdriver is spun, the bit rotates as well. This is what causes the screw to turn. Head style: Torx 40 Length:75mm Hex Shank: 10mm Torx bits are shaped like 6-sided stars, and are utilised on everything from consumer electronics to cars. They are more resistant to cam-out than Phillips or slotted bits and were specifically created for this purpose due to advancements in automatic screw driving tools. Extra Hard bits are suitable for soft fixing. Ie. Screwing into wood and high wear applications