The LSP51 Series fused high pressure steel sight plug has a clear glass sight and male NPT thread connection. The fused, one-piece construction allows for higher operating temperatures and pressures. The sight plug can be accessorized with reflector and float ball. Boxed quantities may apply. Standard Features: Stud end sizes from 1/4 NPT to 2-11½ NPT Fused clear glass sight Body machined from cold finished steel bar stock Electroless Nickel finish Available open view, with reflector or with reflector and float ball Pressure & Temperature Ratings: Maximum operating temperature, 500°F (260°C) Pressure ratings vary by sight plug size, refer to spec sheet for complete details. Caution: Do not use an impact wrench to install a fused sight plug. Not recommended for steam applications. Scratched glass significantly reduces the pressure rating of the sight plug.