Filling cover zinc with male thread.

The lid can be locked on the filler neck with a padlock. The filling cover is normally delivered with a gasket. This secures that the filling cover is tight when the lid is mounted.

Zink DS 7030 ZnAl4Cu1
Reducer: AlMgSi 1.0 (glued on with Loctite 577)
Gasket: DPI-UNI
Thread for 52 mm hoseadapter DS 41
Thread: Pipethread G DS/ISO 228/1