3 years & up. Give young children an easy, fun way to develop their fine-motor skills. This set contains nuts and bolts that pair with one another by both color and shape. Encourage children to match the nuts and bolts and then twist the nut onto the corresponding bolt. In addition to building fine-motor skills, this fun activity will strengthen shape and pattern recognition. Bolts measure approximately 2.5". Includes 72 Plastic Nuts and Bolts Pieces and Storage Box.