Steel Metric Flareless Fitting, 10.00 mm L Series Union Swivel Elbow

This swivel elbow design is intended to allow for rotation during assembly. That makes it easier to line things up when you're dealing with awkward angles or not a lot of space to maneuver.

Swivel is exactly what this is. The fitting rotates during assembly so you can dial in the angle you need before locking everything down, which means your tube stays straight and doesn't take on any torque during the process. That makes it a lot more forgiving in cramped or oddly routed setups compared to a fixed elbow. Once positioned, it holds where you put it, so it works well in mobile equipment where routing paths aren't always predictable.