Final answer:
The GBU-39 Small Diameter Bomb can be configured with different fuzes that allow for selectable Height of Burst (HOB) options to ensure the munition detonates at the most effective altitude for the desired target effect.
Step-by-step explanation:
The GBU-39 Small Diameter Bomb (SDB) is an air-launched precision-guided munition designed to provide aircraft with the ability to carry a higher number of bombs while decreasing collateral damage. The GBU-39 can be configured with different types of fuzes to determine how and when the bomb detonates. While specific details regarding fuzes can be sensitive, information in the public domain suggests that the GBU-39 typically uses a GPS-aided INS and can be equipped with a fuze that allows selection of various Height of Burst (HOB) options.
Different HOB settings enable the bomb to detonate at the most effective altitude to achieve the desired effect against a target, whether that be on impact, above the surface, or with a delay after penetration. The selectable HOB ensures the GBU-39's versatility against a wide range of targets and minimizes unintended damage.