There is memory foam for a comfortable fit.
The straps are held together with velcro.
 
**PLEASE NOTE THESE RUN SMALL** 
If you are not sure please order size up.... Not returnable
 
XS- Women's 5; Kid's 4; China/EU 36; 23.8 cm
S - Womens 7: Kids 6; China/EU 38; 25.1 cm
M - Women's 9, Men's 7; China/EU 40; 26.5 cm
L - Women's 11; Men's 9; China/EU 42; 27.8 cm
XL - Men's 11; China/EU 44; 29.1 cm
XXL - Men's 13; China/EU 46; 30.9 cm