Square nuts have a large surface area, which resists tightening and loosening. Square nuts are commonly used in furniture, metal channels, and railroad applications.Square nuts and hex square nuts have four equal sides. These nuts have a flat bottom side and a chamfered top-side and can be used in a channel or welded in place.The aptly named four-sided square nuts are internally threaded fasteners with a large bearing surface that ensure complete adherence. These durable nuts can easily be installed using a hand wrench