The heavy duty G609 Series front mount closed circuit sight gauges provide front viewing of the fluid level clearly delineated by a redline on white background integral to the glass sight all secured within an aluminum body. Installation is the similar to the G605 Series, but the robust construction of the G609 Series allows these gauges to operate at higher working pressures. Standard Features: Centerline lengths from 5 to12 inches Front mount 1.00 inch SQ body machined from extruded aluminum bar stock Fluid level visible from front of gauge (.62 inch wide) Viewing enhanced by redline on white background integral to sight glass 1/2-20UNF mounting bolts accommodate reservoir wall thicknesses up to .62 inches Suitable for use with most hydraulic and machine lubricating oils Pressure Rating: 600 psi (4137 kPa) maximum working pressure at 150°F (65°C) for centerline lengths from 5 to 12 inches Caution: Not recommended for use with water, steam, acidic fluids, caustic fluids and volatile fluids.