An outer sleeve coupler used in scaffolding is a load-bearing connector designed to join two scaffold tubes end-to-end in a straight line. It is a short steel tube (sleeve) that fits over the outside ends of two scaffold tubes and is secured with bolts or set screws. Once tightened, the outer sleeve coupler holds the tubes firmly aligned, allowing the load to be safely transferred across the joint. Outer sleeve couplers are commonly used to extend the length of standards, ledgers, or transoms when a single tube is not long enough. They provide strength, continuity, and stability to the scaffold structure, especially in vertical extensions.