Guidecraft Magnification Blocks Kids Learning & Educational Toys, Stacking Blocks Hardwood block set with inset lenticular windows for ages 2+ Set includes 6 blocks ranging from 2" to 7" Each block has 2x magnification, stack blocks together to intensify Material: Rubberwood block frames with inset lenticular windows Educational Focus: Science, nature studies, outdoor STEM activities, block play, size relationships