A descendant of the GM series of mobile suits launched by the Earth Federation Forces during the One Year War, the RGM-89 Jegan is lighter and more maneuverable than any previous GM-series model. Although not as fast or well-armed as the previous RGM-86R GM III, the Jegan is an all-around well-performing unit nonetheless. The Jegan mounts a fairly standard variety of weapons, armed with a beam rifle, a beam saber, shield-mounted missile launchers, three hand grenades and an optional head vulcan gun pod. Though initially built by Anaheim Electronics exclusively for the Londo Bell task force prior to the outbreak of the Second Neo Zeon War in UC 0093, the Jegan (and many of its variants) soon become a Federation Forces standard, operating as its primary frontline unit for at least the next thirty years.
information from mechadomain