The blueseventy SwimRun Calf Sleeves are a super buoyant calf sleeve with 7mm neoprene at the front and 5mm neoprene at the back which helps lift heavy legs in the water. These are a perfect addition to your Alliance SwimRun Wetsuit to gain buoyancy for your legs during the swim portions of your SwimRun race without sacrificing freedom of movement during the run portions. In addition, these are a perfect training aid to improve body position in the pool.