I recently purchased this hoping to adjust the OPV on my v3 Rancilio Silvia. I successfully removed the spout and attached the gauge to the portafilter. However, the gauge needle flutters wildly over a ~1bar range. I understand that this is because the Silvia has a vibratory pump. Using a fluid filled gauge or applying a snub or other mitigations would have easily prevented this problem. Unfortunately, this item was not built for use this type of espresso machine pump.