Liquid filled vacuum gauges reduce the effects of pulsation and pressure spikes during measurement. With dampening characteristics that minimize alterations in your reading, it allows the vacuum/pressure gauge to give more accurate results.
Not only does the liquid inside of these gauges help control the effects of vibrations, but the liquid also acts as a lubricant for the moving parts of the gauge. All of those factors plus stainless-steel with reinforced thermo plastic construction makes this one of the most durable gauges for purchase.