Although they may look very similar, carbon fiber is rigid and strong, but shatters easily. Aramid fiber, or “aromatic polyamide” fiber, excels in impact resistance. Aramid shares more similarities with Kevlar, which is used (among other things) in bulletproof vests. Both are aramid fibers, but Kevlar is the brand name of a specific aramid fiber called para-aramid.
Several companies sell aramid cases, including Mous, Pitaka, Latercase, and Thinborne, but equivalent products can also be found on Amazon or Aliexpress.
Some aramid fiber cases are as thick as regular plastic ones, choosing protection over bulk. However, some add as little as a millimeter to the overall thickness of your device. Buying a foldable, every millimeter counts when the device is already pretty thick, and if you are looking to retain the unique selling point of an iPhone Air, a thin case is pretty essential.