Challenge little engineers as young as age 18 months with this set of jumbo 3" plastic nuts, bolts and activity cards. A great tool for the development of color recognition, and learning about shapes and numbers. Builds fine motor skills and finger dexterity as toddlers or older kids spin the nut up and down the dowel. This early hands-on manipulative is durably constructed from polypropene plastic. Extra large bolts measure 2.5" " in length and nuts measure 1.75" x 0.625" , perfect for little hands to manipulate. Set includes 32 nuts and bolts in 4 shapes in 4 colors and 12 brightly colored plastic activity cards measuring 8.27" x 9.45" .