the size of this helmet is the same as the TMNT head, around 45mm. If you ever have a problem with anything you buy from me, for any reason, please contact me immediately so I can work to fix it. I don't want anyone to be dis-satisfied with something they get from me. Leaving negative feedback hurts us all, driving up the cost of listings, which is going to affect the prices I put on items. Give me a chance to fix your problem, whatever it is.