Double barrel shotguns have two barrels arranged either side-by-side or over-under, allowing two shots before reloading. Available in gauges from 20 to 12, they are used for bird hunting, clay shooting, and self-defense. The side-by-side layout is associated with traditional field guns, while the over-under is common in competitive shooting for its centered sight plane and balance. The break-action mechanism has fewer moving parts than pump or semi-automatic designs, which contributes to its mechanical simplicity. Contemporary models use modern materials while retaining the classic two-barrel format.