The G1620 Series back mount closed circuit sight gauges provide front viewing of the fluid level through a clear sight glass. Integral to the sight gauge is a thermometer contained within a white colored card for direct reading of the fluid temperature. The white colored card helps draw eye contact to the fluid level quickly. Standard Features: Centerline lengths of 3, 5 and 10 inches Back mount 1.00 x .95 inch body machined from extruded aluminum bar stock Fluid level visible from front of gauge (.75 inches wide) Clear sight glass Card thermometer (3.00 inch centerline only), dual scale 60° to 180°F and 20° to 80°C graduations Card thermometer, dual scale 0° to 220°F and -20° to 110°C graduations 1/2-20UNF mounting studs accommodate reservoir wall thicknesses up to .75 inches Suitable for use with most hydraulic and machine lubricating oils Pressure Rating: 20 psi (138 kPa) maximum working pressure at 150°F (65°C) Access to inside of reservoir is required to mount this style sight gauge. Caution: Not recommended for use with water, steam, acidic fluids, caustic fluids and volatile fluids.