Also known as the Alto, the Derby missile is a beyond visual range (BVR) air-to-air medium-range (~50 km) active radar homing missile (AAM) developed by collaborative effort between Israeli defence company Rafael Advanced Defense Systems and Israel Aircraft Industries MBT to meet the combat needs of the armed forces.
Though technically not part of the "Python" family, the missile is an enlarged version of the Python-4 with an active-radar seeker.