The airsoft guns used are mostly magazine-fed, with some having manual/battery-powered spring-piston pump powerplants similar to Nerf Blasters, or pneumatically powered by replaceable compressed gas (e.g. propane ("green gas"), 1,1,1,2-tetrafluoroethane or ) canisters. Many airsoft guns also have mounting platforms compatible with genuine firearm accessories, and cosmetically more resembling real firearms. This makes them popular for military simulation and historical reenactments. There are also professional gun safety and weapon manipulation trainings conducted with airsoft in some fields, such as law enforcement trainings, due to better safety and lower cost. The United States Coast Guard, for instance, has officially adopted airsoft for training in 2018.