What are Kheibar Shekan missiles Iran is using to hit US bases?

Iran is using a relatively cheap, flexible-to-use, and accurate medium-range ballistic missile, the Kheibar Shekan, to strike US bases in Middle East. The missile, having range of over 1,400 km, is fired from mobile ground launchers. It can be kept fuelled and loaded quickly onto trucks, reducing launch times. Iran has integrated these missiles with jet-powered drones in new strategy.