Upgrade your tractor or trailer with our Emerald Green Deluxe Screw-On Aluminum Air Valve Knob with Stainless Plaque. The large screw-on knob features a striking emerald green finish and a durable stainless steel plaque. This high-quality knob is sold individually and is available for both tractors and trailers. Enhance the look and functionality of your vehicle with this stylish and practical air valve knob.