Nut drivers look similar to a screwdriver, but have a socket attached to a shaft with an attached handle to turn the tool for tightening or loosening nuts and bolts. The socket fits around and grips around the entire head of the fastener for a secure fit. They provide more contact to the fastener head than an open-end wrench, so the socket is less likely to slip off the fastener when the nut driver is turned. Nut drivers generally have a hollow shaft that allows a threaded bolt to pass through so the tool can turn fasteners on long threaded bolts. They are used for low torque applications compared to wrenches or ratchets that can generate more torque. Nut driver sets come with an assortment of nut drivers to fit a range of fastener head sizes.