CHECK THE SIZE CHART (in the image section above) The Orca Openwater RS1 Thermal Wetsuit is claimed to be better at keeping you warm in the water than any other wetsuit in the Orca range. It features a specially developed inner lining to keep in as much heat as possible for open water swimming. It also has a second layer of 'batwing' neoprene that provides more insulation along the lines of the zip and neck areas, which is effective at keeping out cold water. GARMENT FEATURES: Extra warmth - in the torso, up to 5mm of Yamamoto 39 technical foam provides maximum thermal insulation where you need it most, without affecting the your position in the water or your movement. This material provides 85% more insulation than when you don't wear a wetsuit. The Thermal X high-performance inner lining retains heat more efficiently than standard Orca linings. It is also comfortable and soft to the touch. Yamamoto 40 neoprene- 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 - helping put more power into your swim stroke. To help the wide range of movements made by your shoulders, it offers 72% less resistance than a conventional wetsuit. Batwing' construction- To avoid heat loss in the back through the zip, this model features a 'Batwing' construction made from a second layer of neoprene. This layer prevents water from seeping through the suit's zip and reaching your body, keeping a layer of warm water inside. It also guarantees a comfortable, snug fit in the neck, reducing friction and the amount of water which can get into the suit through the neck area.