What is the difference between single and dual hub tubing assemblies?

Single Hub Flanged Tubing Assembly

A single hub flanged tubing assembly features one fitting (threaded nut and washer) and only one side of the tubing is flanged for compatibility with any flat bottom valve port. The raw tubing end is available as a blunt cut or taper, as pictured below.

Single hub flanged tubing assembly with blunt-cut end.

Single hub flanged tubing assembly with tapered end.

Dual Hub Flanged Tubing Assembly

A single hub tubing assembly features one fitting (threaded nut and washer) and only one side of the tubing is flanged for compatibility with any flat bottom valve port. The raw tubing end is available as a blunt cut or taper, as pictured above.

Dual hub flanged tubing assembly.