These shift knobs feature a precision CNC machined brass core for added weight as well as a white delrin shell for durability, excellent appearance and ‘temperature management’. A heavier shift knob puts the weight towards the end of the shift lever. This increased momentum while shifting gives you a greater mechanical advantage, allowing for a much more positive feeling throw when rowing through the gears. The delrin shell features an anodized cap with an engraved shift pattern as well as an anodized aluminum collar along the bottom of the knob. Since these knobs are delrin, it prevents the surface of the shift knob from getting too hot in the summer and too cold in the winter. These shift knobs make a great addition to your Subaru's interior!