From Halopedia, the Halo wiki
The Drengr armor is a suit of armor employed by the warrior scholars the Skalds.
The Drengr armors were implemented for use in Halo: The Master Chief Collection in Season 8: Mythic. The helmets are available for use in the Halo 3 and Halo: Reach components of the collection, while all other parts of the armor suite are only available for use as Halo 3 permutations.
List of appearances