Note: The Raspberry Pi 4B board and the mSATA SSD on the photo are not included in the packing List. You can use X855 mSATA board with X735 power management board(ASIN:B07R45W1LN) for intelligent and safe power management, safe shutdown and full poweroff through software for the Raspberry Pi 4 Model B.
X855 is only support Raspberry Pi 4 Model B, Supports upto 1TB mSATA solid-state drive (SSD), Only mSATA interface SSD hard disk is suitable for X855 board
Power Supply request: Powered by the Raspberry Pi 4 motherboard (only requires extra power when the SSD can't be recognized or low power)
X855 support USB boot now, please refer to: raspberrypiwiki.com/index.php/X855#FAQ; X855 allows booting OS from your HDD/SSD for faster app opens, web serving and file copying , A micro SD card is required for forcing the Raspbian OS to use the HDD/SSD for its "root" partition
WIKI and document for reference: raspberrypiwiki.com/index.php/X855