The W59 was 16.3 inches in diameter and 47.8 inches long, and it weighed 550 pounds (250 kg). It had a design yield of 1 megaton, with a yield-to-weight ratio of 4 kiloton per kilogram.
A total of 150 W59 warheads were produced during its lifetime.
Historical evidence indicates that these weapons shared a reliability problem, which Hansen attributes to miscalculation of the reaction cross section of tritium in fusion reactions. The weapons were not tested as extensively as some prior models due to a mid-1960s nuclear test moratorium, and the reliability problem was discovered and fixed after the moratorium ended. This problem was apparently shared by the Python primary designs.