Quantum mirror
From Halopedia, the Halo wiki
The Quantum Mirror is a tiny part of the sensor system of the MJOLNIR armor [1]. It is located in the Pauldron of the MJOLNIR armor. The Quantum Mirror in Frederic-104's armor was encrusted with sea salt, causing his Motion Sensor to fail and nearly costing him his life in Havana, Cuba.
