
Samsung Galaxy TabS 10.5
Every official firmware build for SM-T800X, newest first: one row per build with all regions (CSC) that received it.
Box codes of SM-T800X for different colors and markets. Firmware is chosen by the model code SM-T800X and your region (CSC), not by the SKU.

SM-T290N

SM-T537A

SM-T807V

SM-T230X

SM-T230NY

SM-T237V

SM-T232

SM-T530X
You can find the firmware on the model: SM-T800X page.
Yes, all firmware files for SM-T800X are 100% official, original, and obtained directly from Samsung servers.
To flash SM-T800X, you need to download the appropriate firmware, put your device into Download Mode, and use the Odin tool to load the BL, AP, CP, and CSC files.
Downgrading is only possible if the bootloader version (binary bit) of the old firmware matches the current one. Always check the binary version before flashing SM-T800X.