The Chrome Brass Knuckle Tractor & Trailer Air Brake Knobs is a chrome?plated aluminum brass knuckle?style air valve knob that serves as a replacement for worn or plain air brake knobs. Designed to thread onto standard valve stems, this knob features a metal knuckle style with a triple chrome plating process that helps resist corrosion and maintain a polished look. It is sold individually and includes a warranty against defects in materials and workmanship from the date of purchase, though like other special?order parts it cannot be canceled or returned once ordered. While not an original equipment manufacturer (OEM) component, this chrome knuckle knob provides a distinctive, durable option for updating or customizing air brake control knobs on compatible trucks.