US Bomb, 4000 lb Penetrator, BLU-113/B, BLU-113A/B
These are high explosive (HE), hard target penetrator bombs designed to provide penetration capabilities of multilayered hardened underground target structures. The bombs are designed to be fitted with a laser-seeking guidance unit and an airfoil group.
The bombs are painted olive drab. They have one 3.00-inch (76 mm) wide yellow band painted around the forward end of the bomb body. The national stock number (NSN), nomenclature, serial number, lot number, and loading data are stenciled in 0.50-inch (13 mm) wide yellow characters at various locations on the bomb body.
Collaborative Ordnance Data Repository