These fittings are particularly good when you have stainless metal on metal fittings. Sometimes if your MFL fitting is a bit damaged and the seat of the flare is dented your MFL threaded parts may not seal correctly. If this happens this nylon flare/olive is what you need.
It can prevent gas or liquid leaks on your MFL connections. The washer fits inside any of our MFL connections which are on our MKIII multi gas regulators, MFL ball and pin lock disconnects, cold plate, FFL swivel nut and barb and FFL 8mm push fitting.