SRB Aft Segment during transport from the Rotation, Processing, and Surge Facility (RPSF) to the Vehicle Assembly Building (VAB). At top is the External Tank Attach Ring (ETA Ring). On the Aft Skirt at the bottom, the Aft Booster Separation Motors (BSMs) can be seen. The Nozzle Extension can be seen underneath the Aft Skirt. This assembly will soon start the stacking operations in the VAB.