Spectral binders are materials needed to help you combine items and complete collections. You'll use a variety of these for Community Cases, story collections, and local mementos.
You can get different spectral binders by searching certain hidden object scenes or by playing match-3 puzzles.
Tip: If you need a specific spectral binder to complete a collection, you can tap on the missing binder and press "Find." This will take you to a map location where you have a chance of receiving that binder as a reward.