This is a very nice example of a CG45, or Cousteau Gagnon 1945 regulator.  The amount of extra machining as compared to later models is astounding.  Note the 25mm threaded collars on the horns and the mouthpiece.  By 1947 the designation SARL had been restructured by L'Air Liquide so this nameplate  reads SA (Societe Anynome)