The Tractor Air Valve Pin Mount Knobs with Crystal are a practical and stylish addition to any tractor. These knobs feature a pin hole style and are made of chrome plated aluminum for durability. The stainless steel script plate with a plastic crystal on top adds a touch of elegance. Available in a variety of colors, these knobs fit most makes and models. With a 1 23/32" diameter and 1 13/16" tall, they are easy to install and use. Upgrade your tractor's air valve control with these high-quality knobs.