The NRS Chaos Water Helmet is an excellent choice for kayakers, rafters, stand-up paddlers and canoeists looking for safe, economical and comfortable head protection. Durable ABS construction with a BOA adjustment system that is easy to secure. Removable ear pads add additional protection. Sizing: (Head Circumference) Small: 21.3-21.9 in. (54-55.5 cm) Medium: 21.9-22.6 in. (55.5-57.5 cm) Large: 22.6-23.4 in. (57.5-59.5 cm) X-Large: 23.4-24.2 in. (59.5-61.5 cm)This adjustable helmet gives you the features you need and the style you want at a price that won't break the bank. Durable ABS plastic shell dissipates impacts. Dual-density EVA foam provides outstanding comfort and protection. The BOA dial-fit retention harness lets you easily customize the fit for total security. Eight ventilation ports keep you cool on those hot days. Keep the removable ear pads in place for extra protection, or easily remove them for improved hearing. Multiple sizes and quick-adjust harness ensure you'll find the right fit. Meets CE EN 1385 standards for whitewater safety.