The Openwater RS1 Thermal Wetsuit is the wetsuit that provides the most thermal protection of the Orca range. It features a specially developed inner lining to maximize heat retention for open water swimming. It also has a second layer of “batwing" neoprene that provides more insulation down the zipper and neck areas, minimizing the inflow of cold water. Features: EXTRA WARMTH-In the torso, Yamamoto 39 technology which is up to 5mm thick provides maximum thermal insulation where it is needed most, without affecting the positioning of the swimmer or restricting movement. This material provides 85% more insulation compared to not wearing a wetsuit. The Thermal X high-performance inner lining retains heat more efficiently than our standard linings. It is also comfortable and soft to the touch. "BATWING" CONSTRUCTION-To avoid heat loss in the back through the zipper, this model features a "Batwing" construction consisting of a second layer of neoprene. This layer prevents water from seeping through the zipper and coming into direct contact with the body, keeping a layer of warm water inside. It also guarantees a comfortable, snug fit in the neck, reducing friction and water entry from the neck area into the suit. YAMAMOTO 40-Yamamoto 40 is used in the shoulders and back together with the Infinityskin lining. This material can stretch by up to 130%, more than double its original size, providing maximum performance in your swim stroke. For the wide range of movements that occur in the shoulders, it offers 72% less resistance than a conventional wetsuit.