Screwdrivers are the most common of all hand tools, used to fasten and unfasten screws. Screwdrivers are made in many variants, types and sizes, suiting various applications and types of screws. Hex screwdrivers suit hex screws, and Phillips screwdrivers are compatible with the standard, cross-shaped Phillips screw heads. Likewise, Pozidrive and TORX screwdrivers find use to fasten and unfasten the respective screw sets. All these different variants of screwdrivers may also come in various sizes and blade lengths. Screwdriver sets offer a combination of such screwdrivers, either with different screwdrivers in a case, or one handle and several bits. Torque screwdrivers allow tightening to a specific limit, ensuring the screws are neither over-tight nor remain loose. These screwdrivers are used for precision applications, such as to fasten sensitive electronic devices. A few useful accessories for screwdrivers include torque setting screws, screw extractor sets and LED work lamps. Opt for high-quality screwdrivers, such as VDE screwdrivers that are tested and certified for adhering to the correct specifications. The other applicable quality standards are DIN, IEC and ISO standards. The best screwdrivers are made from high-end materials, such as through-hardened chrome-vanadium-molybdenum steel, and have ergonomically designed handles. Screwdrivers with insulation are essential for work in areas with live components and high voltages.