Rugged construction, I bought this tire pressure gauge to measure air pressure in RV tires that are inflated to about 100-110psi. It is designed without batteries, without LCD screen. It's "old school" but made better than anything I've ever had. It is easy to read in sufficient light, but not in the dark. BYOF. πIt comes with a calibration tool to ensure accuracy, but I don't have a "standard" for calibration. If anyone knows how to find a reliable standard for calibration purposes please let