For drivers who want to add style in their cab controls, the chrome air valve knob with stainless steel "Tractor" or "Trailer" plaque is an easy solution that updates worn or plain air valve knobs with a polished appearance. With a chrome?plated finish and topped with a laser?etched stainless steel plaque in a readable cursive font, this screw?on knob helps you distinguish between tractor and trailer air valve functions at a glance. It's sold individually and includes a warranty against defects in workmanship and materials from the date of purchase. Because it's a general aftermarket accessory for heavy?duty trucks rather than an original manufacturer component, confirming that the designation matches your existing valve setup before ordering is recommended.