The Slim Aluminum Type-C Multi-Port Adapter from Satechi is a small dongle that turns a USB-C/Thunderbolt 3 port into an HDMI port, capable of delivering 4K video to any large-screen TV.
What's more, it also has two USB 3.0 ports to connect regular USB devices, like an iPhone, an iPad or a thumbdrive, to your laptop at the same time.
If you use a 12-inch MacBook, which has only one USB-C port, it's helpful that the adapter also has a USB-C port of its own for pass-through charging (you connect your MacBook's power cord to the adapter and it charges your computer) but you can't use the port to transfer data.
The adapter worked well. I liked the fact that it connects to a computer via a short 5.5-inch cable, giving it some flexibility when I moved the laptop around a bit so nothing became accidentally unplugged. An SD card slot would have been a nice addition, but if you can live without that slot, the adapter is well worth its current cost of $60.