Ppu manufactures many calibers of brass cased blank cartridges.Most are "full cased" which means they have an extended case shaped similar to a loaded round.This provides reliable functioning in all types of weapons.This 5.56 nato blank comes in pack of 20 rounds per box, 100 boxes per case.Note: a correct blank firing adapter must be used on the gun to ensure semi- or full automatic operation.Type: BlankCaliber: 5.56x45mm NATORounds Per Box: 20Boxes Per Case: 100Hazair: Yes