For Wired ModMics:
By default wired ModMics are designed to be placed on the left side of your headphones. We recommend you keep the upside-down "U" shape to the ModMic's Boom as when you first received it brand-new, and have the strain relief on the boom pointing downward when your ModMic is mounted. We also recommend you use the included Cable Clips to help give more slack to the ModMic's cable to reduce any strain whether the ModMic is in the “up” or “down” position.
However, you can re-bend the strain relief and attach it to the right side of your headphones as well. Simply straighten the "U" bend and the re-bend it in the opposite direction. Always ensure your strain relief is pointing down to reduce the stress placed on the wiring and use the cable clips to give it enough slack to keep the weight of the cables off the mic.
For the ModMic Wireless:
The ModMic Wireless is designed to be placed on the right side of your headphones with the charging port facing down.