The 310-80 is designed for exterior installation on a trailer with a tri axle air suspension that is controlled by a single height control valve. The 310-80 also provides reliable on-the-ground axle weight measurement with clear readings displayed on its 3-1/2” gauge. The 310-80 features a manual, 3-way bleeder valve to “bleed” air out of the gauge when it's not in use to help ensure the long life of the scales system.