Barrel shrouds are also used on pump-action shotguns. The military trench shotgun features a ventilated metal handguard with a bayonet attachment lug. Ventilated handguards or heat shields (usually without bayonet lugs) are also used on police riot shotguns and shotguns marketed for civilian self-defense. The heat shield protects the user from being burned by a hot barrel and serves as an attachment base for accessories such as sights or sling swivels.