(Night fighters were operating with the so-called Schrage Musik – a pair of 20mm cannons mounted in the fuselage and arranged to fire upwards and forwards at an angle of between 10 and 20º from the vertical. For sighting, the pilot used an extra reflector sight mounted above his head. The installation enabled night-fighter crews to attack from below, from which position the bomber presented a very large target and was almost blind and least able to defend itself. The guns were loaded with non-tracer rounds. Those using it were able to bring down scores of bombers whose crews had no inkling of what was happening until it was too late.)