With the 55M / IFF electronic block (Identification Friend or Foe).
Fully mechanical, wind up clock with 3-day running reserve, 2-day launch sequence indicator,
luminous hands and 24-hour (military time) clock face, built-in 27-volt heater.
Water-proof / vibration-proof, corrosion-resistant steel case withstands 10G's.
ested from -76 °F (-60 °C) to +140 °F (+60 °C). 2¾ inches (7 cm) diameter, 3 inches (7.5 cm) deep.