AEM X-Series -30in/Hg~60 PSI Boost Display Gauge - 30-0308AEMs 30 0308 X Series 30in Hg~60PSI 1~4BAR Digital Boost Display gauge combines incredible looks, increased readability and a multitude of new, easy to use features! It is a must for users who want highly accurate boost pressure readouts up to 60 PSI or 4 BAR in their high performance vehicle. NOTE: The 30 0308 comes with a black bezel and reversible black PSI BAR boost pressure faceplate. You will need to purchase the optional 30 0308 ACC accessory