Another product of the Advanced Bomb Family studies, the JDAM system consists of bolt-on subassemblies that can be added to standard Mark 84, BLU-109B, and Mark 83 bombs to increase their accuracy. The tail assembly consists of the GPS and INS guidance units as well as the control surfaces. It is this assembly that guides the weapon to its target after release. The nose unit is a set of stabilizing fins and plays no role in weapon guidance.