|Body: Steel, black oxide finish
European standard 5.8 grade
Type A - Without thread coating
Type PRB - With thread coating (polyamide overall thread coating)
||Threaded plugs can be used as a spring retention
unit as shown above or as a plug to keep debris from entering
into a critical threaded area.
The PRB thread coating (polyamide overall thread coating) acts as a clamping lock, preventing the locking screw from being inadvertently being loosened and becoming detached.