US Bomb, Guided, GBU-28/B, GBU-28A/B
These are air to surface hard target penetrator guided bombs with a low-level laser guidance system. Target illumination is achieved by a laser illumination device which may be ground mounted or carried in a target-spotting aircraft. The GBUs are designed to penetrate subsurface multilayered hardened underground target structures when a high degree of accuracy is required. The GBU-28/B and GBU-28A/B consist of a WGU-36A/B guidance control group and a BSG-92/B air foil group attached to a 4,414-pound (2,002-kilogram)BLU-113/B or a BLU-113A/B penetrator bomb.
The seeker, the adapter and fairing, the control fins, and the wing assembly are painted olive drab. The control actuator unit and the guidance electronics unit (GEU) are painted brown. GCU markings (nomenclature, part number, serial number, and date of manufacture of components parts) are in 0.25-inch (6-millimeter)-high green (WGU-25/B and WGU-25A/B GCU) or blue (WGU-39/B GCU) characters. Wing assembly markings (nomenclature, part number, serial number and date of manufacture) are in 0.25-inch (6-millimeter)-high green characters.
Collaborative Ordnance Data Repository