The lead element is made up of the flight leader at the very front of the formation and one wingman to his rear left. The second element is made up of an additional two planes, the element leader and his wingman. The element leader is to the right and rear of the flight leader, followed by the element wingman to his right and rear.
Both the flight leader and element leader have offensive roles, in that they are the ones to open fire on enemy aircraft while the flight remains intact. Their respective wingmen have a defensive role - the lead wingman covers the rear of the second element and the element wingman covers the rear of the lead element.
Four of these flights can be assembled to form a squadron formation which consists of two staggered lines of fighters, one in front of the other. Each flight is usually designated by a color (i.e. Red, Blue, Yellow, and Green).
Luftwaffe units used this formation during the Battle of Britain, in which its effectiveness was shown to be considerably greater than the standard three-aircraft "Vic" close formation used by the Royal Air Force (RAF). The RAF and later the United States Army Air Forces (USAAF) adopted this formation and used it themselves against the Luftwaffe.
The finger-four formation became less common after World War II. However, it is still used in the "Missing Man Formation" at pilots' funeral ceremonies. The formation performs a fly-by in level flight over the funeral, at which point the second element leader climbs vertically and departs the formation, symbolizing the departure of the person being honored.