The Chrome Air Valve Knob with US Flag Old Kenworth Logo is a practical and durable product made of aluminum and treated with industrial hard chrome. It is available in octagon or square shape and fits most makes and models. This air valve knob adds a touch of patriotism to your vehicle while providing easy and convenient control over air valves. With its sturdy construction and versatile design, this knob is a reliable and stylish choice for any truck owner.