Sedici Pro Mod Helmet Liner Replacement liner for Sedici Pro Modular helmets. Fitment: Sizes Xs-Lg: Choose the liner size that matches your helmet size, liners are NOT interchangeable Sizes Xl-3Xl: Liners are interchangeable across these sizes OEM Sizing: Xs-Lg: 16mm XL: 16mm 2Xl: 12mm 3Xl: 8mm