Tekton breaker bars have heads that pivot smoothly and continuously through a 230-degree arc. An internal spring controls the tension of the head, allowing it to hold its position while you work. The head is made of AISI 4140 steel and heated to be stronger and more ductile than the handle. Our external head design resists spreading, twisting, or fracturing better than an internal head design. Tekton breaker bars exceed industry standards for Proof Torque, a measure of strength verified by a single-cycle test that applies torque until the specified value is reached without failure or permanent deformation. These breaker bars have comfort grip handles with a rounded oval shape to fit your hand without being bulky. This shape also supports your palm and fingers when you push or pull. The 6135 chromium-vanadium steel core is press-fit deeply into the handle and won't pull apart. Two flat sides on the steel shaft help it resist being twisted or pulled out of the handle. The polypropylene inner handle is rigid and impact-resistant, and the soft overmold grip is abrasion- and chemical-resistant.