The Sensory Blocks Set includes 16 large rubberwood blocks containing beads, transparent acrylic, colored sand and water/glitter filled pockets in 4 different shapes (square, rectangle, triangle and semi-circle). The Sensory Blocks will promote observation in the wider sense, as all the shapes follow the same convention of color and shape. So for example, regardless of the contents of the block the squares are always red. The combination of smooth wood exterior and the brightly colored sensory center makes a fascinating component with a multitude of educational possibilities for use with children of all ages. Size of rectangle: 5.5" x 2.75" x 2" .