LUOM USB C to HDMI Cable 4K 60HZ USB Type C Thunderbolt 3 HDMI Adapter for
iMac 2017 review: Brighter, more colorful, faster, and more powerful | iMore
iMac (Retina 4K, 21.5-inch, 2017) - USB-C - Power & Cables - Mac Accessories - Apple
Amazon.com: Satechi Aluminum Type-C Clamp Hub Pro with USB-C Data Port, USB-A 3.0 Data, Micro/SD Card Reader - Compatible with 2020/2019/2017 iMac & iMac Pro, Does Not Fit 2021 iMac (Silver) :
Satechi Silver USB-C Clamp Hub For 24-inch iMac - ST-UCICHS
Amazon.com: Satechi Aluminum Type-C Clamp Hub Pro with USB-C Data Port, USB-A 3.0 Data, Micro/SD Card Reader - Compatible with 2020/2019/2017 iMac & iMac Pro, Does Not Fit 2021 iMac (Space Gray) :
Are Your MacBook USB-C Ports Loose? - AppleToolBox
Qwiizlab iMac USB C Hub, 6-in-1 Adapter with USB-C 10Gbps, USB-A 5Gbps, SD/Micro Card Readers UHS-I, ONLY for 2021 iMac 24-inch : Electronics
Take a tour: 21.5-inch iMac and 27-inch iMac - Apple Support
Charging MacBook (Pro) with Thunderbolt 3 ports on iMac 2017 | MacRumors Forums