Hawkeye
The Hawkeye is an item in Twilight Princess which lets Link see farther away than usual. It is similar to the Telescope in The Wind Waker, and Link can combine it with the Hero's Bow to be used as like a sniper. The Hawkeye is a one of a kind item that can only be purchased at the Malo Mart in Kakariko Village after completing the bow minigame. It is an optional object and is not required to complete the game.
In Link's Crossbow Training, pressing the "Z" button will activate a zoom similar to the Hawkeye Mask function.