External rings, often referred to as retaining rings, are circular metal fasteners used to secure components onto a shaft or within a housing. They prevent lateral movement while allowing easy assembly and disassembly. Common applications include machinery, automotive systems, and consumer electronics.

The most common types are snap rings (or circlips), spiral retaining rings, and E-clips. Snap rings fit into grooves on shafts and housings, spiral rings provide a continuous 360-degree contact, and E-clips can be installed axially without grooves. Each type suits specific applications based on load, size, and assembly requirements.

External rings are typically made from carbon steel, stainless steel, or spring steel for their strength and durability. For specialized applications, they can also be made from brass, copper, or plastic. Material choice depends on factors like corrosion resistance, load capacity, and environmental conditions.

External rings come in a wide range of sizes, typically measured by the shaft diameter they fit. Standard sizes range from a few millimeters to several centimeters. Custom sizes can be manufactured for unique applications, depending on the load and dimensional requirements.