Hardened External Sensor Array-External
From Halopedia, the Halo wiki
The Hardened External Sensor Array-External or "HESA-E" is a MJOLNIR-compatible device that is attached to the helmet. This equipment is standard-issue in Beta-5 Division security units. The cost of one HESA-E unit is 20,000 credits.[1]
Trivia
- The HESA-E was present in the Halo: Reach Multiplayer Beta, but did not make it into the final game.
- It was most likley not added to the game due to modding, wich may have allowed you to turn on the flashlight, unless this was the creators' intent with the attachment.
Sources