Discovery Toys WORKING TRIO Dump Trucks Take learning about sizes to a whole new level with this set of 3! Friction driven for kid-powered rolling fun. Link or stack the dump trucks by size. Trucks sounds also vary by size. Lift the beds for ratchet sound + rev up for wheel sounds. Turn the loops and hooks for more sounds. Can be used for dump and fill play. Provides hours of imaginary play. From 2 years.