From Halopedia, the Halo wiki
The Threat Sensor, or Threat Detector, is a piece of equipment compatible with the MJOLNIR (GEN3) armor. When deployed, the Threat Sensor emits a periodic pulse in its surrounding area and highlights enemies on the user's heads-up display.
The Threat Sensor is a usable piece of equipment in Halo Infinite. Players can shoot the device to any surface. The device then pulses periodically and highlights enemies in red on the HUD. Enemies are highlighted even when they are obscured by solid barriers.
List of appearances