Airsoft is a combat sport similar to paintball in which participants eliminate opponents by hitting them with 6 mm (or occasionally 8 mm) plastic ball bearings launched from airsoft guns. These airsoft guns can be powered by CO2, Green Gas, air that is forced through a nozzle via a manually cocked spring piston, or mechanical boxes that use motors to pull back and release a spring piston. Participants typically use varying types of weapons designed as replicas of real firearms, tactical gear, and accessories used by military and police organizations. It has been popular in Asia for a long time, and there is now a growing interest in airsoft weapons and events in North America and Europe. Some of the notable manufacturers of airsoft guns include Tokyo Marui, Classic Army, ICS, G&G, G&P, VFC, STAR, Systema, JG, KWA, CYMA, A&K, Echo 1 and others.