This article's name is conjectural. Although this article is based on official information, the actual name of the article's subject is pure conjecture.
Gravity Bands are used in Sonic Riders: Zero Gravity by the characters who don't have an Ark of the Cosmos. Their function is identical to that of the Arks, but they have no importance in the story and are simply used to let every character have access to gravity actions because they are a key feature in the game. Different characters wear their Gravity Bands on different parts of their bodies (with the exception of Amigo, who holds his on one of his maracas and SCR-GP, whose band is inside of its body); Both Knuckles and Shadow wear theirs on their ankles. Tails, Wave, Rouge and Silver wear theirs on their hips. Cream, Blaze and NiGHTS wear theirs as some sort of necklace and Storm wears his on his finger like a ring.