Liquid-Filled Tire Pressure Gauges
The liquid damping in these gauges absorbs shock and vibration to keep the gauge accurate much longer than conventional gauges.
Note: Liquid-filled gauges will have a visible air pocket. The liquid is not intended to completely fill the gauge. Because liquid is mostly incompressible, the air pocket is needed to allow for expansion and contraction with temperature changes. A visible air pocket is not a defect!