My four year old is really into costumes and superheros. He has has at least 20 over the past few years. This is by far the worst quality costume that has been purchased for him. It started fraying at the neck and wrists and getting huge runners after one day.  It runs small. I ordered the 7-8 for my big four year old just to play it safe and the jumpsuit part is just big enough. He usually swims in clothing that size. But the mask is way too small. I tried stretching it gently and it immediately started getting runners just like the junmpsuit. He cried. I am giving it two stars because it looks cool and the jumpsuit part is comfortable. The original package didn't contain a mask, but Amazon corrected that problem and sent out the new package promptly.