These are high quality, accurate gauges designed for critical applications, hydraulic applications, or harsh environments which are subject to corrosion, abuse, temperature fluctuations, or applications with vibration and regular pressure fluctuations. They meet ANSI/ASME Grade 1A requirements, have black and red markings, a 304 stainless steel case, glass lens, glycerin liquid fill (silicone is optional), and either brass or stainless steel internals (stainless have a 316L socket/bourdon tube). The glycerin (standard liquid) filled are rated for -20°C (-4°F) to +65°C (150°F) and the dry gauges are rated for-40°C (-40°F) to +65°C (150°F). Other configurations are available.