You need all parts (Part 1, Part 2, etc.) in the same folder to extract.
The archive name typically refers to the Fatal Frame: Mask of the Lunar Eclipse (Zero 4) fan translation for the Wii. Specifically, it likely stands for "Fatal Frame 4: Mask of the Lunar Eclipse - The Crimson Butterfly's Secret Room" (a common naming convention for certain repackaged English patches). Technical Details Format: RAR split archive (.part6.rar).
If you are missing Part 6, you must download it from the exact same source as the other parts to ensure the checksums match.