1 3/4” external diameter non metallic flexible conduit about 21 ft. Never used.
This is ideal for wiring 2 subpanels together without having to dig through the walls - esp. when connecting the Tesla car charger directly to the main panel.
A comparison from grainger -> https://www.grainger.com/category/electrical/conduit-fittings-strut-channel-framing/conduit-fittings/flexible-conduit-fmc-fnc-fittings/flexible-conduit-fmc-fnc?attrs=Outside+Diameter%7C1.75+in&filters=attrs