Strike Eagle replacement, removable, washable inner liners: Size XS-XXS (SEHPM1210): Loosen the fit in an XS. Size XS (YAEA0102): Can also be used to tighten the fit of a SM. Size S (YAEA0103): Can also be used to tighten the fit of a XS, or loosen a MD. Size M (YAEA0104): Can also be used to tighten the fit of a SM. Size M-L for M shell (YAEA0111): Used to loosen the fit of a MD (the shell size changes between MD & LG). Size M-L for L shell (YAEA0112): Used to tighten the fit of a LG (the shell size changes between MD & LG). Size L (YAEA0105): Can also be used to loosen the fit of an XL. Size XL (YAEA0106): Can also be used to tighten the fit of an XXL, or loosen a XL. Size XXL (YAEA0107): Can also be used to loosen the fit of an XL.