A Star Piece is an item in Pokemon Go that increases the amount of Stardust you earn by 50% for a limited period of time, typically 30 minutes. Star Pieces can be obtained in certain circumstances, such as as rewards for completing Research Tasks or Special Research, or by purchasing them in the in-game store. They can also be obtained in Trainer Boxes or as part of special offers in the store.

To use a Star Piece, you simply activate it, and its effects will last for the duration of the time period. You can stack up to 200 Star Pieces at a time to extend the duration of their effects instead of using one every 30 minutes.

Players can use Star Pieces to maximize their Stardust yield from various sources, such as catching Pokemon, hatching eggs, or completing Research Tasks. It is recommended to use Star Pieces when you plan on playing consistently for the duration of the time period, and to combine them with events where you would most benefit from the increased Stardust yield.