Watercolor Wheel Stack Pack/24Koh I Noor Watercolor Wheel Set Excellent quality and convenient portability make this set a great value. Twenty four brilliant pans of opaque watercolor are neatly stacked in four durable plastic trays that lock and unlock with a twist. The crystal clear plastic lid also doubles as a mixing tray. Each tray represents a range within a color family: Primary Colors, Orange Red, Yellow Green, Blue Earth.