Sonic screwdrivers include a tri-lobe design that fits comfortably in your hand. The poly-carbonate handle is partially-wrapped in a rubber over-mold for grip and additional comfort. A Chrome-Vanadium shaft provides strength, durability, and a lifetime of resistance to rust and corrosion. The hardened magnetic tip provides excellent grip to Phillips screws. Sonic screwdrivers are covered by a lifetime warranty.