On Friday, the FAA gave the aerospace company the seal of approval to incorporate folding wingtips into its new 777X jetliner.

How they work: The tips of the 777X’s carbon fiber wings are mounted on a hinged system that allows them to swing when the plane is on the ground.

Why folding wings? The plane’s 235-foot wingspan is too wide for standard airport gates. Instead of forcing airports to build specialized gates (as Airbus’s 262-foot wide A380 did), Boeing created a wing that adapts to make the tight squeeze.

Why it matters: This could give Boeing a leg up in its battle with Airbus. According to Bloomberg, the 777Xs will be “the first twin-engine models built to haul more than 400 travelers.”