Enamelled steel case with chrome plated steel bezel and acrylic window, sealed Bourdon tube C-type pressure element and ⅜" BSP PM brass connector to HVAC specification. Accuracy : ±1.6% FSD. Also suitable for fluid liquids that are not high viscosity, high temperature (over 60°C) or corrosive to copper/tin alloys. To BS EN 837-1. Gauges used on a permanent basis should be operated in the first 75% of its range, and that a gauge used on an occasional basis may be used over the full 100% of their range.