Fun WorldCount Cutie Costume, Black/Purple, M/12-18 Months

My son is 18 months old and wears anywhere from an 18 month to a 2t will this fit him?

My son is 11 months now (will be 12 months on november 1st) he still fits comfortably in 9 month cloths. what size should i buy? he is 20lbs

Is this true to size? My 18 month old is about 24-25 lbs and currently wears 12-18 month clothing

How do you attach cape? Am I dumb? It has 2 pieces of Velcro but no where to attach. Package says hook and loop fastener dots.