The M-69 incendiary cluster bomb was used to target Japanese cities during World War II. They were nicknamed 'Tokyo Calling Cards'. The bomb used napalm as an incendiary filler, improving on earlier designs which used thermite or magnesium fillers that burnt more intensely but were less energy/weight effective and easier to put out. They were used in clusters of 36 as part of M19 'aimable clusters', which opened up at about ASL.