- FOUR SEGMENT BAYS WITH TWO BAYS ON EACH SIDE OF TRANSFER AISLE.
- HB 1 & 3 WITH EXTENDABLE PLATFORMS USED FOR SHUTTLE ASSEMBLY AND INTEGRATION ON A MOBILE LAUNCH PLATFORM.
- HB 4 CONTAINS SRB AFT BOOSTER BUILDUP STANDS.
- HB 2 & 4 EACH CONTAIN AN ET CHECKOUT CELL AND A STORAGE CELL.
- HB 2 CAN ACCOMODATE ORBITER STORAGE.