The Bag of Infinite Capacity is a unique magical item that allows the user to store any object despite its size or dimensions. Once an item is stored, it can be summoned by merely thinking of the object and opening the bag. The bag can also hold living beings.
The bag can also teleport a user instantly if a user enters the bag.
According to Bailey, she has "always had" her Bag of Infinite Capacity and its true origins remain unclear.
The bag does appear to have a preference for Attaché: