The standard heater connectors are made from plastic and become brittle, crack and leak. Being tucked away under the car it is not easy to detect a leak and can cause a lot of frustration trying to find the source of a leak!
These new parts made to my specifications and replace the plastic ones with a CNC aluminium part that is then anodised for a one time replacement and peace of mind.  Sold as a pair. 
Replaces MG Rover part PFF100040.
Buy similar from Ebay sellers  at double the price!!