A barrage balloon, sometimes called a "blimp", is a large balloon tethered with metal cables, used to defend against aircraft attack by damaging the aircraft on collision with the cables, or at least making the attacker's approach more difficult. Commonly the designs were kite balloons, having a shape and cable bridling which stabilise the balloon in windy conditions, allowing operation in higher winds than a spherical balloon. Some examples carried small explosive charges that would be pulled up against the aircraft to ensure its destruction. Barrage balloons are not practical against very high-flying aircraft, due to the weight of a very long cable.