The Zoggs Buoyancy Flex Jammer 5.3 Short Wetsuit is specifically designed for open-water training and competitions. The jammers lift your hips helping you just like a wetsuit, creating an effect similar to the Pull Buoy and getting a correct position in the water, but allowing you to swim and turn naturally. Buoyancy Flex Jammers have an extremely flexible 5mm Glideskin front base On the back, double 3 mm lining improves abrasion resistance.