The Ametek/US Gauge 155355 is a 1903 SOLFRUNT Series process gauge with a 15 psi pressure max, 4.5" dial size, 1/4" NPT lower back mount connection, brass wetted material, and aluminum case material. The Models 1903 and 1933 4.5" process gauges are designed for process applications that require a panel mounted gauge. The 1903 and 1933 gauges have a cast aluminum front flange case with a lower-back mount process connection. These models are available with wetted surface material in brass/phosphor bronze and 316L, depending upon your needs.Calibration adjustments (scale shape and span) can be accomplished from rear of case without disturbing the gauge internals. Pointer adjustments are easily made by removing ring and window.