"This costume comes with everything you need. I think it would be a little snug for a 4 year old. My daughter is 33lbs and 3 ft. tall. She had plenty of room just if she was any taller we would really have to stretch it out. Thats why I only gave it a 4 instead of a 5 because of the sizing. And it shipped super fast.. I ordered Sunday night and got it by Tuesday afternoon.. I"