Sliding Top Box (The Thinker Play Kit): Designed for 11–12 month olds. Your baby drops a ball into a hole on the wooden top, where it disappears. They then have to form a mental image and slide the top to reveal and retrieve the hidden ball. Wooden rectangular box with a sliding lime green lid. Includes a turquoise wooden ball. Simple, modern toy design. Bright colors and smooth finish. Good Used Condition