To check the right size helmet to buy, it is sufficient to measure the circumference of the forehead, using a meter from tailors. You have to place the meter height eyebrows, then pass it an over the ears, as shown in the following image
CHANGE YOUR SIZE:
If you want to change the size of a helmet already bought, well send it to: RAMO Srl - Via Masoni, 86 - 80141 Napoli (ITALY). Inside the package insert a request to change size and your address. The size change is free.