This Hosco Tremolo Arm is for our Hosco Mustang tremolos and has a '65 Fender Mustang style arm angle. It has a 5 mm diameter and is not threaded to suit push in style arm holders, the arm is made from steel and comes with a black knob/tip. Tremolo arms are one of the most likely things to be missing when buying used guitars so we have made these available as spares to easily get your tremolo back up and running.