I bought my PEX Tubing here

It also requires fewer fittings than traditional systems and pipelines. PEX works for the two water lines: cold and hot. It is available in red, which can be used to indicate the hot and cold blue. This is not necessary, is only for convenience of the user. Another advantage of its amazing flexibility is the ability to expand and to contract. This makes PEX much less prone to breaking or cracking.