A barrel block is a family of safety devices that mechanically obstruct the end of the marker's barrel. They are intended to ensure that, should all other safety devices incorporated in the marker fail or be deactivated, a paintball fired by the marker will not leave its barrel and cause injury. Barrel blocks are usually required by commercial fields, to be used on any marker that is in an area where masks are not required. Neglecting to replace it after leaving a game and entering a safe zone will usually earn a warning. Repeated infractions will often result in ejection from the site. This is done for liability reasons and to lower possibility of unexpected injury to anyone around, especially important when involving eye safety. There are two common types of barrel block:
