*Due to hygienic reasons, all helmets are final sale. Dive Into the S1 SIMBA’s Sentinal provides full head coverage without compromising freedom of underwater movement. Weighing in at just 372 grams the S1 is one of the lightest Watersports helmets available. ◉ Impact Resistant ShellEngineered to protect all areas of the head specific to Watersports injuries. ◉ Low-Profile Shell & Cut-OutMinimum water drag and optimum peripheral vision. ◉ Advanced Ear Protection SystemAids in the prevention of Surfer's Ear and perforated ear drums. ◉ Low-Profile ChinstrapSecure, comfortable positioning using non-corrosive materials. ◉ Removable Halofit Pads™Allows for custom sizing. ◉ Innovative Layer-Tech PaddingFor extra protection and interior impact absorption. ◉ Interior Padding Channel DesignAllows water to quickly drain out after submersion. The Sentinel 1 is offered in 3 sizes: S – 52 – 54 cm M 55-57 cm L 58-62 cm Your SIMBA helmet should fit like a baseball cap. The objective is to fit the helmet snugly to your head. If your measurement is at the maximum for size SMALL or MEDIUM (54cm or 57cm) we recommend moving up to the next size. HOW DO I MEASURE MY HEAD?Use a cloth tape to measure the circumference of your head. Ideally the measurement should be taken approximately 1/2″ above your ear. If you are in between sizes, or wear a hood that would increase your circumference measurement, we recommend you select the next size up.