This is a file format specifically designed for storing Wii game backups on external hard drives or SD cards. It is more efficient than a standard ISO because it removes "padding" data, making the file significantly smaller.
The ghost Mii bowed. Then it turned and walked off the rooftop, dissolving into falling cherry blossom petals as it fell toward the glowing neon sea. Wii Sports Resort -WBFS- -RZTE01- -NTSC- -wiiGM-