Guide to Mac, iPad, iPhone ports: Lightning, USB-C, Thunderbolt & more | Macworld
Sabrent HB-SIMC Multi-Port USB 3.0 iMac Hub at MacSales.com
Fastest Thunderbolt 3 External Storage for iMac Pro: EveryMac.com
Plugable USB 3.0 Universal Laptop Docking Station Dual Monitor for Windows and Mac, USB 3.0 or USB-C, (Dual Video: HDMI and HDMI/DVI/VGA, Gigabit Ethernet, Audio, 6 USB Ports) - Walmart.com
Anker 535 USB-C Hub (5-in-1, for iMac) - Anker US
What are the ports on your MacBook? - Laptop/Mobile Service Center