Easily monitor your fuel pressure with these plug and play kits. These FAST fuel pressure gauges are designed to fit most aftermarket billet fuel rail kits, especially the FAST LSX fuel rail kits. They conveniently install on the end of the fuel rail for an easy way to monitor fuel pressure, which is critical to achieving ultimate performance with your fuel injected engine. With their black gauge face, liquid-filled internals, and easy-to-see indicator needle, these gauges are easy to read and durable. Best of all, their high-quality, heat-resistant silver casing delivers an ultra high-tech appearance that enhances any engine compartment. Full instructions will get you up and running in no time. Best of all, you'll never have to guess as to the state of your current fuel pressure ever again.