Which type of screw features threads designed specifically for metal fastening?

The correct answer is sheet metal screws, as these screws are specifically designed with threads that facilitate fastening thin sheets of metal. The thread design of sheet metal screws is sharper and more pronounced, allowing them to penetrate and grip metal surfaces effectively without the need for a pre-drilled hole. This makes them ideal for applications in metalwork where a strong hold and secure fastening are required.

Wood screws, on the other hand, are intended for use with wood, featuring coarse threads that help grip the softer material but do not perform well in metal applications. Lag screws are heavy-duty fasteners typically used for securing large wooden structures and cannot be used effectively in most metal settings due to their design and purpose. Carriage screws have a smooth, rounded head and are used primarily in wood to secure materials, not optimized for metal fastening. Therefore, among all the options, sheet metal screws are the only type designed specifically for fastening metal.