Stainless steel case Brass internal Glycerin filled Back connection Good quality Liquid filled Pressure Gauge:Case sizes: 1.5", 2", 2.5", 3", 4 ... BSPT dependent on model and size; bottom, back, left and right side connection Available ranges: vacuum and compound through 500psi, 600psi, 5000psi ... , metric scale, DIN 2.5% accuracy, U-Clamp, restrictors. back connection glycerin filled Pressure Gauge