Duel Gazer

A Duel Gazer, known as a D-Gazer (Ｄ－ゲイザ, Di - Geiza) in the Japanese version, is a device in Yu-Gi-Oh! ZEXAL which is worn over a person's eye. It allows the wearer to watch duels in an augmented reality setting.

In anime, they have been shown to be used as communicators, such as phones. They have also been shown to link together two different Duel Gazers for Duels and allow any other Duel Gazers to link to the Duel to see it. This most likely allows spectators to follow just one Duel even if there are multiple Duels using Augmented Reality occurring in the local area.

Like Duel Disks and Duel Runners, Duel Gazers have a standard version (light grey with blue lens), but also has different design colors, and different versions can be adapted with glasses as seen with Flip. Nelson Andrews' Esper Sparrow mask can be connected with a Duel Gazer in a similar way as Flip's glasses.

Duel Gazer Tattoo
Some Duelists use special tattoos found at their left eye in place of a Duel Gazer. When activated, it spreads around the eye, forming into a shape that's unique to every Duelist.

Kite Tenjo is the first Duelist seen capable of Dueling without a normal Duel Gazer. Consequently Trey, Quattro, Quinton, Dextra, Nistro, and Luna are capable of being able to Duel like that as well. When Trey receives special powers from Vetrix, his tattoo starts to glow, and cover more of his face.

In addition, although Astral does not need a Duel Gazer to Duel, his left eye is golden, as opposed to his light blue right eye, which is similar to the fact that a person wearing a Duel Gazer tattoo over their eye has their left eye color change.

Trivia

 * Quinton and Kite were also seen using regular Duel Gazers in a flashback.
 * In the anime, Cathy wears glasses, but instead of using a special model to be attached on it as Flip, she just removes her glasses and wears a normal mechanical Duel Gazer.
 * It seem as though, while a Duel Gazer only covers one eye, the Duelist sees only Augmented Reality while wearing it.
 * Trey's, Quattro's, and Quinton's tattoos are all secondary colors (orange, green, and purple). Interestingly each individuals clothing and their hair color consists of the primary colors (red, yellow, and blue).
 * Thunder Spark used nothing in his eyes during a Duel, and they didn't seem to change in any way. It is unknown if he still was able to see the Augmented Reality Vision or if he wasn't able to see it at all.