Typhoon Helmets Breath Box G339 Adult Modular Helmet (Sizes Small, Medium, Large) Breath Box for size Small, Medium & Large Typhoon Helmets G339 Adult Modular Helmet. Please see our other items for a breath box made to fit the same helmet in sizes XL and XXL. Will only fit the specified helmet model Items returned for refund that have originally been shipped with free shipping will recieve refund LESS our original shipping cost.