Zinc-plated.
Seal on imperial thread with sealing edge in acc. with DIN 3852-2 Form B. Seal with sealing cone X in acc. with ISO 8434-1 (24° cone) or 8434-6 (60° cone). To seal the screw-in side, it is possible to use a copper seal, DIN 7603 Form A which prevents reflection of the screw-in hole.
Warning: Do not use Teflon tape! Copper seal 1/8 order no. 69815 Copper seal 1/4 order no. 69823