Thread-sized inserts are a type of fastener that is used to create a threaded hole in a material that is not naturally threaded. They are made of a hard material, such as brass or steel, and they have a threaded shank that is designed to be threaded into a drilled hole. Thread-sized inserts are available in a variety of sizes and materials. The most common materials for thread-sized inserts are brass, steel, and nylon.