Samsung Gear S (SM-R750P) Firmware Overview
The archive lists 2 official builds for the Samsung Gear S across 1 region (CSC). The newest one is R750PVPU1APB1, released February 25, 2016 with Android 2.2.1.4. It is a feature update on bootloader binary 1: once a phone runs it, firmware with a lower binary can no longer be flashed (how to read a build number).
How to Flash SM-R750P Firmware
Put the Samsung Gear S into Download Mode, load the BL, AP, CP and CSC files into Odin on a Windows PC and press Start. Pick a build with the same or a higher Bit than the one installed — a lower bootloader binary will be rejected.