The new MacBook Pros (and the 12-inch MacBook) only uses USB-C ports for its connections. So if you want to connect anything other than a USB-C device, you'll need a dongle. And the SMK-Link USB-C Multi Port Hub is the dongle that connects them all.
Despite its small size, once plugged in, it instantly turns any USB-C port into multiple peripheral ports, including three regular USB 3.0 ports, one SD card slot, one miniSD card slot, one HDMI port and one Gigabit Ethernet port. It also has one USB-C port for pass-through charging; necessary if you use it with the 12-inch MacBook, which has just one USB-C port for both charging and data.
The hub connects to a computer via its 5.5-inch long dongle allowing for some flexibility. This means when you move the laptop around, you're less likely to accidentally disconnect from any devices.
There's only one catch, with a suggested retail price of $99, it's one of the most expensive dongles. However, I've seen it online for as low as $80. But since it has pretty much every port, it's well worth the investment.