This hard to find bottle adapter is the one you need for use with on a cylinder of R1234YF /HFO1234YF refrigerant – 1/2″ acme left hand female fitting to a 1/4 Flare Male.

This will fit the Dupont R1234YF Cylinders – the Honeywell Cylinders have a 22mm thread on them and this will not be suitable.