A swivel is a connection that allows the connected object, such as a gun or chair to rotate horizontally and/or vertically. A common design for a swivel is a cylindrical rod that can turn freely within a support structure. The rod is usually prevented from slipping out by a nut, washer or thickening of the rod. The device can be attached to the ends of the rod or the center. Another common design is a sphere that's able to rotate within a support structure. The device is attached to the sphere.… (More on Swivel)