This is a machined metal aluminum spine, meant to fit in the back of the helmet of an AT-AT Commander, or AT-ST Driver. It comes with two threaded holes and appropriate machine screws to attach to the back of your helmet.
Note: The spacing and fit has been confirmed to fit MonCal helmets. Other manufacturers may have different spacing and may not work without significant modifications.
Perfect addition to your helmet for the best accuracy, and a Spearhead requirement for 501st costumes!