Carriage bolts, or carriage screws, have a square neck that keeps them from turning once tightened. These bolts have domed heads. Use in square holes for wood-to-wood and wood-to-metal fastening.
Elevator bolts are similar to carriage bolts, except they have a flat head, which gives them low head clearance. Their square neck keeps them from turning once tightened.
Eyebolts have a looped head that can be forged with or without weld seams, closed or unclosed, and may have a shoulder to better support angled lifting. They are used for lifting, attachment, and for tie-downs.
Flange bolts have a flange under the head which distributes the clamping load over a greater area.
Hex bolts are hexagonal-shaped and feature a chamfered, or grooved, point to aid insertion into a tapped hole or nut.
Lag bolts are similar to wood screws; they have threads designed to bite into the surface and resist pull-out. Lag bolts are larger than wood screws and are usually used to hold two pieces of wood together.
T-slot bolts have heads designed to fit into machine table slots; these bolts won’t twist or jam and provide a larger bearing surface.
Toggle bolts have winged supports to anchor a bolt to a wall stud or ceiling joist. To insert, fold the toggle wings flush with the bolt, and push the bolt through a drilled opening until the wings pop open on the other side.