Apple has released a support page that outlines different adapters users can purchase to connect with Thunderbolt 3 to their new 2016 MacBook Pro with Touch Bar.
The new MacBook Pro features four Thunderbolt 3 ports, which use the same connector as USB-C. If you are using an existing Thunderbolt 2 peripherals, you will need the Apple Thunderbolt 3 (USB-C) to Thunderbolt 2 adapter.
If you are looking to connect devices like digital cameras and thumb drives, you will need to purchase a USB-C to USB adapter. For connecting your new MacBook to an external monitor, you will need either a USB-C Digital AV Multiport adapter or a USB-C VGA Multiport adapter.
To charge and sync your iPhone with your new MacBook you will need to purchase a USB-C to Lightning Cable.
Late-2016 MacBook Pro models will vary slightly in the data speeds that are provided to each of the Thunderbolt 3 ports. On the 15-inch model, all four ports deliver full performance.
However, on the 13-inch model, the two ports on the left side provide full performance, while the two ports on the right deliver Thunderbolt 3 functionality with a reduced PCI-e bandwidth. This means that you will not get the full speed Thunderbolt 3 is supposed to deliver.
Apple advises that users connect higher-performance peripherals to the Thunderbolt 3 ports on the left side of the 13-inch model. For reference, higher-performance devices can be considered as external storage or external monitors. It appears that the limitation is mostly due to the integrated GPU found on the 13-inch model, while the 15-inch model’s dedicated AMD GPU is powerful enough to provide full performance across all four ports.