3 years & up. Children can easily collect, curate, experiment with, and display found objects and liquids with these sturdy, clear acrylic Treasure Tubes for 360 degree viewing. Removable covers make it easy to add trinkets, natural materials, and sensory objects to observe, display, and rattle. Ideal for color and sound exploration and light table activities. Holds marbles, beads, twigs, leaves, small toys and more. Stack the tubes on top of each other to customize play experience. Easy-to-remove wooden top keeps objects securely in place until ready to be replaced. Set of 8 tubes. Largest Tube measures: 3" diameter x 5.75"H. Smallest Tube measures: 3" diameter x 3.5"H.