DIN (Deutsches Institut für Normung / German Institute for Standardization) Union
The DIN Union is comprised of a round slotted nut, male part, a liner, and a gasket.
The male part and liner that comes in contact with the product come in SS 304 and SS 316L while the round nut is SS 304.
The gaskets comes in Teflon, BUNA, EPDM, Silicone, and Viton.
The easiest way to identify an DIN Union is its D Shape Gasket.