Why PEX Tubing? PEX stands for cross-linked polyethylene which is a type of plastic tubing used in plumbing and hydronic heating systems instead of copper tubing. Crosslinking is obtained through a chemical process that increases the bonds between macromolecules to form a more complex structure than normal polyethylene. As a result, PEX tubing, also called PEX Pipe, performs better and maintains excellent properties of thermoplastics. Familiar red, white or blue PEX tubing is incredibly tough and flexible, corrosion resistant and fast and easy to install. Looking for PEX tubing – look no farther. We have the products and the technical knowhow to help you use them.