In order to connect an 8 mm pipe to the outlet valve on a 4-hole tank, you will normally need to flare the end of the pipe and use a flare nut. This fitting screws to the valve and allows a simple compression joint to an 8mm copper pipe without the need to flare the pipe. It is designed to fit outlet valves with a large thread (12 mm). If you are buying a set of valves from our shop, this flare nut will fit. This fitting is made from 2 parts that allow the flare nut to be undone without having to disconnect the pipe.