AC to USB adapter to charge the laptop and the screen, together with other devices (check the second picture) I have a similar device but for different plug formats and currents/voltages (international traveling). It has been a great addition, not only because it works for both set ups (travel and remote office) but because it allows me to move around the apartment I am working from while at meetings. I sometimes carry an stencil instead of this battery but I love the flexibility this multi-power and multi-port device provides me so I can combine the “travel” and the “remote office” set ups in a single backpack.