A/C valve stems

[OverCorrupt]

So my A/C had been losing some power since this summer began and so i decided to check the system. Was at .43kg instead of the .50kg spec. Checked for leaks and my Low pressure valve stem is leaking slowly.

Tried searching it on here but to no avail. A/c and ac is removed from search so it only pulled up tire valve stems.

So the question i am asking is, has anyone replaced them or know the size of the valve stem? looks like its R12 but i dont want to match em from just a pic online.