Ametek Crystal M1 [M1-30PSI-BXX-W] Digital Pressure Gauge, 1/4" NPT male, 0 to 30 PSI w/ Pump System B (Pneumatic) -0.85 to 2 Bar & Waterproof Case. The Crystal M1 Pressure Gauge maintains 0.2% of reading accuracy from -10˚ to 50˚C. Accuracy is not affected by dropping, over-pressure, vibration, temperature, or rapid pressure change.