This set offers a variety of driver bits for everyday use as well as rare applicationsMade of premium grade S2 tool steel, these bits are heavy duty, designed for hard usePremium grade S2 tool steel durable composition equals longer bit lifeHeavy duty quantities multiple quantities of the most commonly used sizesDriving bits designed for quick-change applicationsMagnetic drive guide helps reduce slipping and wobble by holding long fasteners in place while the sleeve retracts as the screw is driven into the material