Our "500 TX" size will be deployed in 4 sizes in all. 
Depending on the size you choose, the size (outline) of the helmet will not change. 
The size of the helmet (hat body) is one size @ 1 size. 
Sizing is done by interior (inner). 
This interior is fixed like a normal helmet, and between "helmet and interior," EPS "for impact absorption is used as lining material. 
"EPS" is a specially formulated blowing agent, which is adopted as a shock absorbing material for helmets of all riding standards.

Please be aware that our 500TX is not a standard helmet for getting on a ride, so there is no shock absorbing capacity equivalent to a standard helmet for boarding 

The interior size adjustable size is "XS size" "S size" "M / L size" "XL / XXL" size

About size measurement (standard size)

How to measure your head
Head Measurement Line

1 - Measurement Method

※ Please measure your head circumference at the yellow line position, as shown in this image
※ Wrap the measuring tape around the fullest part of the head - this will be just above the ears and about a half-inch above the eyebrows for most - and take the measurement at the forehead
※ Although there are individual differences, if it is measured at this position roughly it seems to be the best choice for size
※ To get the most accurate measure, have a friend help with this step
※ As there could be measurement adjustments / errors, try to measure 3 - times and calculate the average value

2 - Conforming Head / Helemt Size

※ Recommended for people up to 54 cm in size XS → head circumference 
( those who are mostly women, those who think the head circumference is smaller)

※ S size → head circumference Recommended for people up to 56 cm 
( people who generally think that head circumference is smaller)

※ M / L size → head circumference Recommended for people up to 58cm 
(mainly the standard size of general men)

※ XL / XXL size → head circumference Recommended to those up to 60 cm 
(Those who think that the head circumference is largely larger, depending on the shape of the head, there are 
results that have been suffered by 61 cm or 62 cm)