This small spring loaded valve fitted with a tiny O-ring stops the DragonFly Stove from becoming flooded with fuel.
It fits on old and new Pumps. It is not required on the Standard Fuel Pump used for other stoves.
It measures 28mm long including the spring.
Part Number: 418712.
Unfortunately, it is not possible to buy the O-ring on its own, at least not from MSR.