90 degree right angle adapter - 1/4" BSP brass adapter.
Right hand thread form.
This brass fitting has been cleaned to oxygen safe standard and comes with a 1/4" BSP male thread to a loose 1/4" BSP female nut.
While it is safe for use with oxygen it can also be used on inert gases such as argon, nitrogen and CO2 which all utilise the same right handed thread.
The last image you can see the end of the bullnose from the connection inside the loose nut. It is a true gas fitting connection rather than something else. No PTFE is required as they should be brass on brass sealing.