Great Fairy's Mask
The Great Fairy of Power in the Fountain in North Clock Town bestows the Great Fairy's Mask to Link when he returns the single Stray Fairy from Clock Town to the Fountain while he is in Hylian form. The Stray Fairy is located in the Laundry Pool in South Clock Town during the day, or floating near the pole in the center of East Clock Town during the night.
When in dungeons, the Great Fairy's Mask shimmers when Link is in a room that contains Stray Fairies. If the Fairy is floating freely (not contained in a chest, jar, or bubble), the Great Fairy's Mask makes a small chime and attracts the Stray Fairy to Link automatically.