Goggles

Goggles are used as the traditional symbol for the 'leader' of a digidestened team. they are normally worn aorund the forehead, and as of yet (only in fanfiction has this happened) no female has ever worn goggles in the whole series of series.

Apparently, the goggle wearer usually is the most upfront person, more willing to fight when others give up. They are referred to sometimes as 'goggle kid(s)'

In Digimon Adventure
In the first series, Taichi Kamiya wore goggles.

In Digimon 02
At the beginning of the second series, Tai passed his goggles onto Davis, who eventually lead the team of Yolei, Ken Ichijoji, Cody, and older T.K. and Hikari(Kari).

In Digimon Tamers
In this series, Takato wears the goggles.

In Digimon Frontier
In this series, Takuya wears the goggles. He later actually uses them in a sandstorm in the Digital World.

In each series, excluding Savers, the 'goggle kids' usually have a dragon or reptile type digimon.