 "U-28" was armed with two bow torpedo tubes and could carry a complement of four torpedoes.She was also equipped with a 75 mm/26 (3.0 in) deck gun and an machine gun.After intricate political negotiations to allocate production of the class between Austrian and Hungarian firms, "U-28" was ordered from Cantiere Navale Triestino (CNT) on 12 October 1915.