DetailsThis custom made lock nut has an O-ring grove for a size 212 O-ring. It's the perfect lock nut for a watertight seal though your kettle wall. The groove give O-ring the perfect 20% compression to guarantee a good seal and long lifespan. The fitting completely covers the O-ring to protect it. This locknut has NPSL thread, which is a thread spec for locknuts to work with NPT.