This provides a way for you to safely store your airsoft GBB's similar to how real firearms are stored. The chamber flag works by preventing the slide or bolt from completely moving forward, making you unable to shoot it. It does so by seating itself slightly inside the barrel and staying in place when the slide/ bolt presses against it. If you want to shoot, simply pull the slide/ bolt back and take the flag out. It is also designed in a way to allow for you to still be able to lay the gun flat on its side for normal storage. At the moment, this works best on Glock Series pistols and M9 Series pistols, but from the pictures, you can see that it could work with others. DM me if you want a video that shows how to use it Purchase comes with 2 Chamber Safety Flags