You can use these to momentarily blind and deafen people. Enemies that turn away before the blast won’t be affected, and even the ones that have been ‘got’ are still able to run away or shoot you. Damn.
A good way to make the enemy dazed and confused, giving you time to follow up with a hail of bullets or a sneaky knife kill. More effective than Flash grenades, as enemies don’t need to be facing the blast.