U 81 to U 83 had one 10.5-centimetre (4.1 in) deck gun with 140-240 rounds. U 84 - U 86 were constructed with two 8.8-centimetre (3.5 in) deck guns. In 1917, U 84 - U 86 were converted to a carry one 10.5 cm and one 8.8 cm deck gun[2] and carried 240 rounds.