This is a defective item.  The shirt rips on the sides after just a few minutes of wear.  I thought maybe I had a bad one, so I got a replacement.  The 2nd one ripped in the exact same way.  If you are seamtress, maybe you can stitch the side seams before they rip.  Once they rip the costume is a mess and unwearable and then you have a sad little girl to deal with.