My son is big for his age, always has been. So he's a three year old the size of a 4 year old. That said, the child size "S(4-6) fits a little big, which I like so I don't have to worry about him growing out of it too soon. The pant sleeves are too long for him and should be taken in (which I don't do, so oh well). The material is comfortable and (slightly) breatheable (compared to other costumes out there) but a bit light (which is perfect for warm weather but if you are buying this for a chilly halloween, I recomend long sleeve clothing underneath). I also bought him inflatable Buzz wings to complete the look, but they never stay on longer than the first few minutes after arriving at a party. Due to the lightness of the material I do wash the costume by hand, but only because I want to prevent any issues with the machine breaking it. I HAVE washed it once or twice in the machine when it was particularly dirty, and it survived the wash, but I wouldn't recomend that as the main cleaning method.

Over all, the kid loves it, and I am totally getting my money's worth by letting him wear it around the house when he wants to play rather than just once in the year during halloween.