Moon Sand is really nothing to get excited about. Moon Sand does harden if left for a long period of time. It is very messy.  They claim that it is neater than sand and easier to use than playdoh!  NO WAY!  It is sand, like wet sand at the beach.  It allows you to make things and build sand castles but is definitely is not like playdoh.  I wouldnt waiste my money or if you do only let the kids use it outside.