GBA Time Ring
The GBA Time Ring is a Magical Ring that Link acquires in Oracle of Ages. There is no possible way to acquire the ring in Oracle of Seasons directly, but it can be acquired through a Linked Game by using the Ring Secret.
When playing Oracle of Ages on a Game Boy Advance console, Link has access to the Advance Shop in Lynna Village. There are three items available for sale in the Lynna Village Advance Shop. From left to right, there is a Gasha Seed, the GBA Time Ring, and another Seed Ring.
When equipped, the GBA Time Ring has no effect at all. This is simply just a symbolic ring given to those who play the game on a Game Boy Advance console. A similar ring can be found in Oracle of Seasons in the form of the GBA Nature Ring. That ring, similarly, has no effect when equipped.