The Joint Direct Attack Munition (JDAM) is a guidance kit that converts unguided bombs, or "dumb bombs" into all-weather "smart" munitions. JDAM-equipped bombs are guided by an integrated inertial guidance system coupled to a Global Positioning System (GPS) receiver, giving them a published range of up to . JDAM-equipped bombs range from to . When installed on a bomb, the JDAM kit is given a GBU (Guided Bomb Unit) nomenclature, superseding the Mark 80 or BLU (Bomb, Live Unit) nomenclature of the bomb to which it is attached.