Samsung Galaxy Folder (SCH-W899) Firmware Overview
What is the latest SCH-W899 firmware?
W899HD18, released April 18, 2014 with Android 2.3.6. The archive holds 2 official builds across 1 region (CSC). Each one is the full stock ROM (flash file) for Odin, not an OTA patch.
Is the Samsung Galaxy Folder still getting updates?
Most likely not: there has been no new firmware since April 2014, so Android 2.3.6 is the last version this model got. The final builds below are still the best choice for a clean reinstall.
All SCH-W899 firmware builds
How to Flash SCH-W899 Firmware
Put the Samsung Galaxy Folder into Download Mode, load the BL, AP, CP and CSC files into Odin on a Windows PC and press Start. Use HOME_CSC to keep your data, CSC for a full wipe.