It is used for all models of Koshin high-pressure pumps to shut off an unused additional pressure outlet. Has a thread 1 inch BSP (25 mm). 

One pump requires two sets of 0118009 Seal coupling assemblies. Includes: 0110422 Coupling, 0120485 Sealing plate 25 mm and 0110192 Coupling packing (gasket).

Suitable for  SERM-50V, SERH-50V, SERH-50Z