4000Kcal British Army Ration Box Menu 1 24 Hour Ration pack produced by the suppliers to the British Armed Forces. The 24 Hour Ration Pack (4000 Kcal) is a complete one stop ration to fully sustain 1 active person for 24 hours while on operations. It contains high energy snacks, electrolyte drinks and 3 main meals. All meals are fully cooked and ready to eat, hot or cold.