a high strength reinforcing bar splice uses a contractible jaw assembly bridging the bar ends to be joined . the jaw assembly includes interior teeth designed to bite into the projecting ribs or deformations on the outside of the bar ends which form the overall diameter of the bar but not the core or nominal diameter of the bar . the jaw assembly is constricted from both axial ends by driving tapered locking collars on each end of the jaw assembly with a tool while concurrently causing the jaw assembly to constrict and bite into the bar ends . when the tool is removed , the collars remain in place locking the jaw assembly closed . the splice provides not only high tensile and compressive strengths but also has good fatigue and dynamic strength to qualify as a type 2 coupler .