Helmet recorder

Helmet recorders are standard field issue equipment for many UNSC Marines. When in combat with 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 the 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 Recorder Chips.

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