This compression fittings has inside a full metal compression ring made of CW 617N brass. The body and the clamping nut are made of the the same brass. The fitting do not have any plastic or rubber gaskets. These fittings allow to make compression, dismountable connections with copper pipes. Some of the fittings (those marked in the code with letters FD) have a wide (min. 3.0 mm wall thickness) flat face on the side with the threaded connection. This allows the fitting to be connected directly to a flexible, corrugated hose or to make another connection using a flat gasket. Compression fittings with a solid ring for copper pipes meet the requirements of EN 1254-2.