Body: Steel, European material property class 5.8 grade,
zinc-plated, blue passivated finish, ultrasonically checked
Seal: NBR synthetic rubber
The seal is retained in a groove undercut in the mating face,
which prevents it from dropping out and from extruding when
the plug is tightened. For this reason the seal can be of
a softer material which offers better sealing.
NBR seal: maximum heat resistance: 120°C (250°F).