Cost-effective option: Pairing PI4B Adapter with CB1, the function is close to the Raspberry-Pi 3B. With Bigtreetech motherboard, you can run the Linux system efficiently. The most value way using Klipper! When matching with the Raspberry Pi CM4, the function is exactly the same as the Raspberry Pi 4B. Board to board connector: Use the same BTB connector as Raspberry-Pi, perfectly compatible with the various versions of the Raspberry Pi CM4, and easily install the CB1. The 40-PIN GPIO interface is compatible with the Raspberry Pi ecology to meet more DIY needs.