A flexible tubing having a PEX inner core (102) is surrounded by a reinforcing structure, such as a braid (104). The reinforced flexible tubing meets NFPA Standards for the installation of Sprinkler Systems (13/13R/13D) in both residential and commercial buildings. The reinforced flexible tubing is suitable for a variety of other high temperature/high pressure applications. The tube's flexible characteristics facilitate its installation at a greatly reduced cost, especially in retrofitting existing structures. An adhesive can be used to improve the overall strength and stability of the reinforcing structure surrounding the PEX core. Optionally, a protective outer layer (106) can be applied over the reinforcing structure.