I simply can't find the answer but I'm sure someone here must know. The diameter of the inner tubing is 5mm (sorry about the dog hairs on the 1st pic , it's that time of year :/ )
Thanks for replies...Seems they are 'Crossover Copper Bends/Fittings' used, as you say, for air conditioning...I've found them online once I knew what to look for specifically. Appreciate all the help, best ring the scrap man