Ptolemaic Companions and Antigonid Companions were also equipped with a large round "aspis" cavalry shield unlike the Companions of Phillip and Alexander. ‘Companions’ was a title not used by the Seleucids in its original sense. It was replaced with different and various grades of ‘Kings Friends'. However, the title 'Companions' was kept as a regimental one. There was only one regiment or unit that held the title of Companions in the entire Hellenistic world though; the Antigonids and Ptolemies had different names for their elite cavalry regiments. The "Hetaireia" or "Hetaeria" was a corps of bodyguards during the Byzantine Empire. Its name means "the Company", echoing the ancient Macedonian Companion cavalry. The imperial "Hetaireia" was composed chiefly of foreigners. They acted as part of the Byzantine imperial guard alongside the "tagmata" in the 9th–12th centuries.