Seac OCTO SYNCHRO X100 Octo, X-5 Octo and Octo Synchro: Seac offers solutions for a reliable and durable emergency second stage that allows natural effortless breathing. Even if the specs differ, the common denominator is always maximum functionality. Octo Synchro material: ultralight technopolymers . X100 Octo material:technopolymers,elastomers and ultralight alloys (Hi-Flex hose included) X-5 Octo material:technopolymers, elastomers (Hi-Flex hose included)