SRT, SRT Modular

 

Size CM IN HAT SIZE (IN)
XS 53-54 20 7/8–21 1/8 6 5/8–6 3/4
SM 55-56 21 1/2–21 7/8 6 7/8–7
MD 57-58 22 1/4–22 5/8 7 1/8–7 1/4
LG  59-60 23–23 1/2 7 3/8–7 1/2
XL 61-62 24–24 1/2 7 5/8–7 3/4
XXL 63-64 24 7/8–25 1/4 7 7/8–8
XXXL 65–66 25 5/8–26 8 1/8–8 1/4