
Samsung Gear S3 Classic
Every official firmware build for SM-R770, newest first: one row per build with all regions (CSC) that received it.
Box codes of SM-R770 for different colors and markets. Firmware is chosen by the model code SM-R770 and your region (CSC), not by the SKU.

SM-R765N

SM-R870

SM-R750J

SM-R885F

SM-R861
You can find the firmware on the model: SM-R770 page.
Yes, all firmware files for SM-R770 are 100% official, original, and obtained directly from Samsung servers.
To flash SM-R770, 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-R770.