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PEX compression fittings are designed to connect PEX pipe, which is flexible, durable, and corrosion-resistant. These fittings feature a compression nut and a compression ring (commonly called a ferrule) that creates a watertight seal when compressed onto the PEX pipe. This compression mechanism eliminates the need for welding or gluing, making PEX compression fittings a popular choice among professionals.
link:https://www.ifan-plast.com/brass-fitting/pex-fitting/
IFAN PEX Brass Compression Fittings