Zoggs Pull Buoy is designed to isolate the upper body. Improving upper body strength and stroke technique. The ergonomic construction sits comfortably between your thighs to immobilise your legs. Can also be held between the ankles which will make for a more challenging workout for your torso and upper body as you try to keep your body straight whilst swimming. The Pull Buoy is best used with hand paddles to further focus on improving upper body strength and stroke technique.