A Robe is an Otome's powered suit. It provides her with super-strength, the ability to fly and materialize her Element, and, apparently, life support in outer space or at least above the upper atmosphere assuming the Mai-Otome universe still applies most of the rules of the normal world. Most Robes have prehensile ribbons or coat tails, the number of which vary, and some are used for support or extra appendages while some can be used offensively as blades. Most Robes also have distinctive glowing ring-like structures around the ankles and wrists as well as other glowing accessories on other parts of the suit. They usually glow when in flight. A few robes have extra unique abilities such as Sara's, which can turn invisible.
Robes are voice-activated. Once the GEM is unlocked by the master, the Otome can materialize the Robe by saying "Materialize!" The GEM then displays the initials of the Otome and her master, as well as the gemstone-themed code name of the GEM/Robe, and proceeds to materialize it.
Robes provide considerable physical resistance even to the apparently unprotected head but are not completely failsafe. Under sufficient external force (or simply from overexertion, as seen with Arika in episode 4), a Robe may shatter, although it is unknown if this completely suspends all of the Robe's abilities, as Arika and Nina somehow survived re-entering Earl's atmosphere in episode 26 even after their Robes completely disintegrated. Also, if the GEM's connection to the master is disturbed, the Robe will disappear leaving the Otome with her clothes before she activated her Robe. However, this process is reversible if the Otome comes in physical contact with her formal Master. She would immediately regain her Robe. This shown during episode 25 when Arika regained her Robe after clasping hands with Mashiro, her formal Master.