Swivel fittings connect tubing to a threaded hole. The barb (and tubing) can be freely rotated from the base. An integrated sealing bead provides a convenient and cost-effective seal against the mating part. Barbed connections are a clean, time-tested, and cost-efficient method of connection. The hoop strength of the tube holds around the barbed fitting. Air Logic's first barb is free of a parting line to create a good seal, additional barbs increase holding force for tube retention. PVDF (Polyvinylidene Fluoride) is a High-end Engineering material for demanding applications. Here are some of the reasons we use it at Air Logic. Extreme chemical resistance: weak and strong acids, oxidizing acids, mixed acids, organic solvents. Outstanding mechanical: high strength, creep resistant, impact-resistant, very low water absorption, abrasion-resistant, very dense, and durable. Stable: Ozone resistant, UV resistant, UL-94 V-0\. Suitable for ultra-pure applications: no leachables or extractables. Suitable water applications: Ultra-pure, Deionized, Distilled, or Demineralized water systems. Suitable for highly corrosive applications.