Boeing 787-8 —

General Electric GEnx, which powers the B787-800, Dreamliner, and a bleed version powers the B747-800i and B747-800F. To the left of the image, just out of frame is the Low Pressure section of the Engine, the middle is the High Pressure Section, to the right, just in shot is the Turbine Section. The metal bands, on the outside of the Turbine Section, is diverted air that cools the Turbine casing which helps reduce the gap or clearance between the Turbine casing and blades which are shrouded, increasing efficiency, I am told.