For GTA: San Andreas , the OBB files are typically named main.8.com.rockstargames.gtasa.obb and patch.8.com.rockstargames.gtasa.obb . These files work together; the main file is the primary game data, and the patch file serves as an update or expansion to the content. Both are to be present and correctly placed for the game to run. When looking for downloads, the OBB is the large data file, and the APK is the smaller installer. The APK itself is quite small (around 15-57 MB), while the OBB file is significantly larger, requiring about 2.5 GB to 3 GB of storage space.