For added flexibility, Expansion Pans fit into the brush slot, increasing your capacity from 12 up to 15, 16, or even 18 colors while keeping the same compact, pocket-friendly form. The Expansion Pans set includes single-cavity pans that hold approximately 2.25 ml (close to a full pan) and twin-cavity pans with two 1.1 ml wells, ideal for splitting colors or adding smaller accents.