M19-B surface-to-air missile launcher
From Halopedia, the Halo wiki
The M19-B Surface-to-Air Missile Launcher is a man-portable, shoulder-fired anti-aircraft, guided munitions launcher in service with the UNSC Defense Force. The launcher fires surface-to-air missiles, capable of destroying Type-26 Banshees with relative ease. The weapon is ineffective against Type-31 Seraph fighters due to their energy shielding system.
At the time Halo: Ghosts of Onyx was written and published, the M41 rocket launcher was officially called the M19 surface-to-surface missile launcher, despite the weapon's in-game models bearing the former designation. After years of confusion, Halo: The Essential Visual Guide clarified that the weapon itself is indeed the M41 SSR, while the M19 surface-to-surface missile is its ammunition. Thus, one may infer that the M19-B SAM is not a rocket launcher at all, but rather a dedicated anti-aircraft variant of the M19 SSM. To wit, it may be the version featured in Halo: Reach and Halo 4, as the rocket launchers in those games can track aircraft but not ground vehicles.
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