Collar studs, also known as collar bolts, are a type of fastener that are used to act as a shaft or dowel for the rotation or sliding of attached parts, including pulleys, gears, and mechanical assemblies. They have an unthreaded cylindrical section, or “shoulder”, between the head and the threaded section. This shoulder allows for precise alignment and spacing of components. Collar studs are available in a variety of materials, including mild steel and stainless steel. They are also available in different finishes, such as black oxide, passivated, and thermal black oxide. Collar studs are used in a wide range of applications, including automotive, aerospace, and industrial machinery. They are often used in applications where precise alignment and spacing of components is critical, such as in the assembly of engines, transmissions, and other mechanical systems.