0.170" ID, 1/4"OD Nylon 11. Some people use air brake hose. Lots of people like to replace it with stainless covered line. The Nylon 11 needs to be pressed on. Hold the pipe with a clamp of some sort, you will not be able to hold it in your hand, put some oil or lube in it and drive the banjo into it with a hide or rubber mallet. Do not heat it except maybe with hot water, shouldn't be necessary.
Dave
69S