The Calibrator

SM04: The Calibrator is a side mission in Deus Ex: Mankind Divided. It is available for Adam Jensen to complete during his first visit to Prague, and must be also be completed during the first visit (i.e., prior to visiting Golem City). While this side mission has an achievement, it has another name and depends on the path you take, which means you could miss it (and another achievement) entirely.

Walkthrough
You get this mission after talking with Koller and he tells you about the neuroplasticity calibrator that could help Jensen use all his augmentations without choosing which ones to disable. Unfortunately, the one who has it, Otar Botkoveli, is not exactly on speaking terms with Koller, so you have to go get it from him.

There are two ways to get the calibrator, but only the first has the option of opening up more missions and achievements later in the game.
 * Head to the alley behind Tubehouse Electronics to find a sewer entrance with a poker chip paint job. Enter and follow the rugs to the casino entrance and open the door. This will lead to a cutscene of Jensen overhearing Otar talking to one of his men, Vano, before Jensen walks in. Select straight talk all three times and then accept and he will give you the calibrator in exchange for a couple favors down the road. Now all you have to do is head upstairs to Otar’s office and retrieve it off his desk.

Whichever option you went with, once the calibrator is in hand, Jensen will contact Koller to let him know he got it and the mission will finish.
 * If you do not want to deal with Otar and the later favors, you can sneak your way in via a number of ways to get to Otar’s office.  Instead of being on his desk though, it will be in the safe (4863).  You will also have to make sure to stay cloaked or carefully time taking out the guards to access the safe (or just kill everyone).