A sleeve nut(barrel nut) is a type of fastener that has internal threading and is used primarily in furniture making. It’s also known as an insert nut or threaded insert nut because it can be inserted into pre-drilled holes for a secure fit. The most common types of sleeve nuts are made from steel, stainless steel, aluminium, brass, and plastic. They come in various sizes, shapes, and thread counts, so they can be used for different purposes.

Here are some of the most common uses for sleeve nuts(barrel nut): 

Woodworking Sleeve nuts are also useful in woodworking projects to add strength to joints or other attachments that may experience heavy loads or wear over time. For example, they can be used to attach lids or doors securely to boxes without having to use drilling screws directly into the wood itself. 

Electrical Work When working with electrical wiring, sleeve nuts can provide insulation between two connected components and reduce shock hazards when exposed wires touch each other accidentally. They also help reduce vibrations from electric motors or devices that run at high speeds by providing extra support to wires connected together inside conduit pipes or similar structures.

Furniture Assembly Sleeve nuts are commonly used in furniture assembly because they can be inserted into pre-drilled holes for a secure fit without damaging the material underneath. They act as reinforcement against the weight or pressure placed on the furniture piece. 

A sex bolt is a type of mating fastener (nut) that has a barrel-shaped flange and protruding boss that is internally threaded. The bolts sits within the components being fastened, the flange provides the bearing surface. The sex bolt and accompanying machine screw sit flush on either side of the surfaces being fastened.