Mechanical Monster gauges are crafted with lightweight aluminum and match the hardcore look and performance of Pro-Comp gauges. Easy to view 3-3/8-inch size allows quick glance engine monitoring for both competition and custom pro-street applications. Choose an electric voltmeter or fuel level gauge to match the rest of your Monsters for awesome performance and a great look. Requires braided stainless steel line and mounting cup. Gauge must be mounted outside of vehicle.