Sabrent Premium 4-Port USB 3.0 Hub for iMac (2012 and later)
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M1 iMac 2021 - USB-C HUB with Hard Drive Enclosure– The Apple Nest
4-Port USB 3.0 Hub For iMac - Sabrent
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) :
Type-C Clamp Hub Pro | iMac Expansion Adapter - Satechi
HOPDAY iMac USB Hub, 6 in 1 USB C Hub Adapter for iMac 24 Inch 2021 iMac Accessories with 4K HDMI, 10Gbps USB C and USB 3.1 Gen2 Type-A, SD/TF Card Readers