What is the MK-124 primarily used for?

The MK-124 is primarily used as a signal device that provides both smoke and illumination. This versatility allows it to be effective in various scenarios, enabling personnel to signal for help or communicate their location under different environmental conditions. The smoke can be used during the day to create a noticeable visual signal, while the illumination feature is intended for nighttime use, allowing the signal to be visible when the natural light is reduced.

The inclusion of both capabilities—smoke for daytime visibility and illumination for nighttime—highlights the MK-124's design to function effectively in a broad range of situations and times of day. This dual functionality is crucial for tactical operations, where the ability to signal can be needed at any time, depending on the mission or emergency situation.

This answer elucidates why the MK-124 is characterized as a signal device that combines these two functionalities, distinguishing it from options that only emphasize one aspect or the time of day it is used.