M19-B surface-to-air missile launcher
From Halopedia, the Halo wiki
The M19-B SAM Missile Launcher is a heavy ordinance weapon used by the UNSC it fires high-powered surface to air missiles and was deployed in limited numbers for UNSC ground forces in the 2540's and early 2550's. However, they were not widely used, as their counterpart model, the M19 SSM (SPNKr) Rocket Launcher, was much more versitile and portable on the field.
This weapon was used by Alpha Company and Beta Company. It is for the most part ineffective on a Covenant Seraph-class starfighter, but effective against a Banshee.