The RPG-series of weapons is the most widely used family of lightweight antitank weapons in the world today. RPGs have been used not only against their intended targets, but against personnel, fortifications, buildings, soft-skin vehicles, watercraft, and aircraft. Lightweight, relatively compact, easy to operate and maintain, they meet most of the requirements of any armed group. Like any weapon system, RPGs and their ammunition have their limitations. While these limitations are much touted by proponents of more advanced weapons, they lose sight of many armed groups' requirement for lightweight, compact, inexpensive, easy to operate and maintain weapons. Most sophisticated weapons tend to be just the opposite – heavy, cumbersome, excessively expensive, and requiring extensive training and an advanced support infrastructure. They are also more difficult to obtain due to export controls and restrictions. To be effective, an army actually needs a mix of both sophisticated and uncomplicated weapons. Gordon Rottman provides a detailed analysis of perhaps one of the most important weapons to be developed in the 20th century.