7th Shock Troops Battalion
From Halopedia, the Halo wiki
The 7th Orbital Drop Shock Trooper Battalion was one of many units of UNSC Orbital Drop Shock Troopers in operation in 2552. Members of this battalion were stationed aboard the UNSC In Amber Clad during The First Battle of Earth. It is they who traveled to Installation 05 and "Helljumped" to the surface along with the Master Chief. They are the only living ODSTs seen in the Halo 2 video game.
On Cairo Station, the bodies of several ODSTs are found in air locks, but it is unknown if these ODSTs belonged to the 7th Battalion or not. Later, during the Battle of Installation 05, First Platoon of the group stationed on the In Amber Clad was sent along with the Master Chief to the surface to clear a landing zone. Unfortunately, they landed right in the middle of a Covenant fortified complex, and within seconds all but three of the Platoon were dead. The remaining ODSTs helped the Chief as he traveled towards the Prophet of Regret's Assault Carrier, but all three were also killed along the way.
NOTE: The battalion number comes from a patch that was designed for Halo 2 and intended to be used on crew members of the In Amber Clad. The patch was shown along with the In Amber Clad patch in the book The Art of Halo. It is not clear whether or not this patch was ever actually seen on the shoulders of any characters, as the In Amber Clad logo was.
