From Halopedia, the Halo wiki
The seeker drone is an explosive homing drone in service with the UNSC Armed Forces. It is used as an armor plug-in by SPARTAN-IV supersoldiers. Once deployed it flies toward an enemy; if no enemies are found, it self-destructs after six seconds. A small device, it flies using a pair of turbines. Its status (active or inactive) is denoted by a light on the cowling.
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