18 months and up. Combine loose parts activities and numeracy skills with the Loose Parts Number Trays. Made from easy-to-clean plastic, these trays are the perfect addition to any loose parts play environment. The trays' see-through plastic keeps items visible, accessible, and organized while also encouraging sorting, seriation, counting, and more! Introduce an additional layer of sensory exploration by shining a light source through the clear plastic. Smallest tray measures 6""L x 1.4""W x 1""H. Largest tray measures 6""L x 4.3""W x 1""H.