This board has a 1 Gbps Ethernet port and features 2x MIPI-Camera connectors. It also has an M.2 M-key slot capable of using NVMe SSDs or other PCIe peripherals. It has a full size HDMI port, an RTC with battery backup (Version B and C), and a 4-pin fan connector with a fan controller (Version B and C). It also has 2x USB 2.0 ports and a built-in USB 2.0 hub.
Waveshare Industrial IoT Wireless Expansion Module Designed for Raspberry Pi Compute Module 4 : Electronics
Waveshare CM4-IO-BASE-A Rev3.1 in Baden-Württemberg - Kraichtal
Design Your Own Raspberry Pi Compute Module PCB : 5 Steps (with Pictures) - Instructables
Dual Gigabit Ethernet Carrier Board for Raspberry Pi Compute Module 4 - Seeedstudio 102110497 Botland - Robotic Shop
Waveshare Raspberry Pi Official Compute Module 4 IO Board A Development Platform and Reference Base-Board Design for CM4
CM4-IO-WIRELESS-BASE - Waveshare Wiki
Raspberry Pi Compute Module 4 IO Board with PoE Feature (Type B), for all Variants of CM4
HDMI Signal Extender, 1080P High-definition & lossless transmission, up to 50m
Waveshare CM4-IO-BASE-BOX-B, 45.90 €
Raspberry Pi Compute Module 4 Development Kit, With Official Io Board, Basic Accessories, And Optional 7 Touchscreen - Demo Board - AliExpress
Mini Base Board/Mini-Computer Full Version, Designed for Raspberry Pi Compute Module 4, USB HDMI Adapter Optional
A Computational Comparative Analysis Between Nvidia Jetson Nano and Raspberry Pi CM4 for the Classification of White Asparagus with SVM