Our flexible shafts are used in a range of construction tools, especially concrete vibrators, which rely on flexible shafts to deliver torque to the vibrating head inside a concrete form.Normally, these flexible shafts have a median core diameter of 0.250 to 0.625 inches (6.35mm to 16mm), with a carbon steel core. The core rotates within the casing, and is constructed using multiple layers of helically wound wires.