market to accept a "plastic gun" due to durability and reliability concerns, as well as fears that metal detectors in airports may not detect the polymer frame, Glock pistols have become the company's most profitable line of products, commanding 65% of the market share of handguns for United States law enforcement agencies, as well as supplying numerous national armed forces, security agencies, and police forces in at least 48 countries. Glocks are also popular firearms among civilians for recreational and competition shooting, home and self-defense, and concealed carry or open carry. The FN Five-seveN, is a 20+1-round, semi-automatic pistol designed and manufactured by Fabrique Nationale d'Armes de Guerre-Herstal (FN Herstal) in Belgium. The Five-seveN pistol was introduced in 1998. It was developed together with the FN P90 personal defense weapon and the FN 5.7×28mm cartridge. Developed as a companion pistol to the P90, the Five-seveN shares many of its design features: Lightweight polymer-based weapon with a large magazine capacity. Ambidextrous controls, low recoil. Ability to penetrate body armor when using certain types of ammunition. The Five-seveN is currently in service with military and police forces in over 40 nations. In the United States, the Five-seveN is in use with numerous law enforcement agencies, including the U.S. Secret Service. In the years since the pistol's introduction to the civilian market in the United States, it has also become increasingly popular with civilian shooters. Machine pistols A machine pistol is generally defined as a handgun capable of fully automatic or selective fire. During World War I, the Austrians introduced the world's first machine gun, the Steyr Repetierpistole M1912/P16. The Germans would quickly follow suit with machine gun versions of the Luger P08 "Artillery Pistol" and later models of the Mauser C96. Their light weight, small size, and extremely high rates of fire made machine pistols difficult to control in full-auto. Most machine pistols support a shoulder stock to improve control, like the Heckler & Koch VP70. Others, such as the Beretta 93R also have a forward hand-grip. Overview of gun laws by nation Many handguns are easily concealed — a trait that is useful both to civilians wishing to bear arms for self-defense and to criminals wishing to carry a handgun for illegal purposes. For these reasons, handguns are a particular focus of debates on gun politics, and in many jurisdictions handguns fall under specific restrictions. See also Action Antique firearms Gunspinning