Reinforcement couplers are components which connect two reinforcing bars in longitudinal direction, forming a mechanical splice. This is an alternative to lap splices or welded connections. Mechanical splices are used to avoid protruding bars in casting joints, reduce congestion in confined spaces and to save rebar length. Reinforcement couplers are used in reinforced concrete structures to replace normal rebar lap joints. The couplers are also suitable for use in reinforced concrete columns and walls.