The Indigo Blue Aluminum Screw-On Air Valve Knob with Stainless Plaque is a practical and durable addition to any tractor or trailer. Its indigo blue finish adds a touch of style, while the large screw-on knob with stainless steel plaque ensures a secure fit. This product is sold individually and fits most makes and models, making it a versatile and convenient option for those in need of a reliable air valve knob.