SPECIAL ORDER ITEM. Review Returns Policy before purchase. This stainless steel insert stiffener is designed to reinforce flexible plastic tubing connections used in water service applications. It helps maintain tubing shape and prevents collapse when compression or connection fittings are installed. Manufactured from 300-series stainless steel, it offers corrosion resistance and long service life. The stiffener is suitable for polyethylene, PEX, and polybutylene tubing systems and meets common waterworks standards for safe potable water use.