Helmet recorder

The view from a recorder.

Helmet recorders are standard field issue equipment for many UNSC Marines in the field. When in combat with any other enemy, moreover the Covenant, they are instructed to turn these recorders on to get as much information on the Covenant as possible. Because such data is scarce, this is an invaluable tactical resource to ONI and the UNSC forces, who often retrieve this data and then debrief the wearer about the audio and video data they recorded. They store their information in the processed Recorder Chips.

Apparently, Covenant Ossoonas are equipped with similar helmet-mounted recording units.