HRC 200 Series T-Headed bars are manufactured by a friction-forging process, under strict quality control to ensure a zero-slip connection between head and bar that exceeds the actual tensile strength of A706 reinforcement bar. Head sizes are in accordance with ASTM A 970 (1997-2004) and Caltrans Full Size (9Ab) to transfer the full rebar force into multi-axial stresses in the concrete beneath the head without crushing the concrete or bending the head. Conservatively used when 4Ab heads are required.