A Factsphere Sensor is essentially an advanced camera that relays live thermographic images and data to the pilot. They are usually protected under a retractable layer of armor. When retracted it allows for greater system sensitivity. Earlier generation Knightmare Frames typically place a single Factsphere sensor on the head of the unit, while later models place one on each shoulder. Some later models have no visible sensors at all. Lelouch's Shinkirō, has a single Factsphere sensor mounted on its forehead without retractable armor, due to its absolute defense system. A similar scaled down system can be seen on some special infantry (like Private Kururugi) as a HUD-like system used to relay video feeds, enhance low light visibility, and identify objectives. This infantry system is helmet-based and is located on the brow, using two periscope-like eyepieces that cover the eyes to allow viewing.