The LSP501 Series low pressure aluminum sight plug has a clear glass or polycarbonate sight and a reflector machined into the plug body. Sight options include screen printed level lines. An economical alternative to threaded sight plugs requiring only a reamed hole or equivalent to provide a secure fit. Box quantities may apply. Standard Features: Sight diameters from .56 to 1.56 inches Sight: Clear or with level lines Body machined from aluminum bar stock Available in sight material and level line combinations Pressure & Temperature Ratings: Maximum operating temperature up to 180°F (82°C). For applications requiring maximum operating temperatures in excess of 180°F (82°C), consult factory for available options. 25 psi (172 kPa) maximum operating pressure at 69°F (20°C) Caution: Not recommended for steam applications. Scratched glass significantly reduces the pressure rating of the sight plug.