This is absolutely the best toy we own!  My autistic 2 year old sons are playing with it constantly.  I have to put it away occasionally, so they can play with other toys too.  As soon as I bring it back, they rush to it and fight for gears.  I also bought an amusement park addition and now 2 sets of refrigerator gears.  If you only buy one toy for your toddler, this is it!!!