I have been having a read around but am still not clear about the best thing to do when speccing and installing air line. In my workshed, I eventually want to end up with a rigid pipe setup from the compressor to the point that the airlines to the tools plug in. This system seems to be recommended by a fair few people - https://pipefittingsdirect.co.uk/contents/en-uk/d29.html What determines whether 15mm is best or 18/22/28?? When it comes to the flexible lines from the rigid pipework to where the tools are being used again, i have the same question? There seems to be 1/4", 3/8", 1/2" and even 1" flexi pipe although the latter two seem fairly hard to get in the UK with 3/8" ID pipe being most common? How do you spec what you need here - is it related to the tool or compressor or the pipe run or something else?? Finally, if you have say 3/8" pipework but a 1/4" ID fitting on it, how much of an effect does that have? Do the fittings need to be paired in some way with the pipe? Sorry if these are silly questions, but i dont want to go out and spend a load of money and find i have done the wrong thing!