Hex coupling nuts are a versatile and useful type of fastener

Hex coupling nuts, also known as extension nuts or connector nuts, are a type of fastener that are used to connect two male-threaded parts together. They are typically made of a strong and durable material such as steel or stainless steel, and are shaped like a hexagon (six-sided) with threads on the inside. They are designed to be tightened by a wrench on the hexagonal part of the nut.

Hex coupling nuts are often used in plumbing, mechanical and electrical systems, and construction. They are particularly useful when it's necessary to connect two threaded rods, screws, or other parts that need to be coupled together. They can also be used to extend the length of a threaded rod, when two or more of them are screwed together.

Hex coupling nuts are available in a variety of thread sizes, and are usually classified by the size of their threads which ranges between fractional inches to millimeters. They are available in different materials such as steel, stainless steel, brass, and plastic. They come in different finishes like zinc-plated, black oxide, and hot-dip galvanized.

Overall, hex coupling nuts are a versatile and useful type of fastener that can be used to connect two threaded parts together. They are strong, durable, and come in a variety of thread sizes and finishes to meet different application requirements.