Pre-insulated AquaPEX tubing is Crosslinked polyethylene with a little extra: The tubing comes with a layer of pre-attached 1/2-inch foam that saves energy and up to 37 percent on installation costs compared to the traditional installation and insulation process. It’s available in 1/2- to 2-inch sizes and 20- and 100-foot lengths. Cost: from $4 to $13 per foot. Uponor Corp. 800-321-4739.