I made them for future projects
They are supposed to go on to a 14mm pipe and go on the back of a cabover like the Tamiya Volvo, or the Tamiya Scania... So if you want to put them on your roof you should go with the smaller size of 12mm I've made as well. The small size would fit perfectly to the intake of a conventional truck like the king hauler (one on each side of the bonnet). They look pretty much the same but with slightly different dimensions. Only problem is that I havn´t got elbows ready yet. Using the straight connectors, elbows, and a pipe you can put them wherever you want.