This 20mm, Plastic, 90 degree water connection socket, comes as a set of 2 and includes the 16x2 Orings.
These water connection sockets are used on the following Hydronic S3 water heaters: B4E 20.2007.05.000, D4E 25.2933.05.0000 & 25.2943.05.0000, B5E 20.2008.05.0000, D5E 25.2993.05.0000, 25.2934.05.0000 & 25.2942.05.0000.