Couplings can be used as extensions or to change the angle or gender of a fitting. These also include adjustable length couplings for Crossfire / SLI setups and RAM block connectors.
Adjustable Length (5)
Primarily for SLI / Crossfire water cooling setups, adjustable length couplings are able to bridge small gaps which would normally be difficult with tubing. Other adjustable couplings are used with Koolance RAM coolers.
Angled couplings allow for quick changes in tight spaces, usually immediately after an inlet or outlet port. Most can be rotated for optimal positioning to avoid conflicts with other components.
Fixed Length Straight (12)
Straight couplings are used as gender changers or as fixed extensions or spacers. Swiveling versions can be freely rotated.