Designed specifically for open water training and races. The jammers lifts your hips up like a wetsuit and helps you find the right water position. You will achieve same effect as using a pull buoy, but it allows you to kick and turn naturally. The Buoyancy Flex Jammers has a front 5 mm base of extremely flexible Glideskin very useful in the swimming session while the back 3 mm bi-lined neoprene has been conceived to improve abrasive endurance and to reduce the risk of scratch. More elasticity. Drawstrings at the waist. Unisex model. Materials Outer: 50% Double sided Flex and 50% Glideskin neoprene  Inner: Nylon and Polyester lining 100%  Composition: 90% Neoprene, 8% Nylon, 2% Polyester