FINIS Tech Toc Hip Trainer Provides instant stroke feedback and ensures proper hip position during all four swim strokes. Uses a ball bearing in a plastic capsule and acoustic amplifiers to create a sound as the device is tipped from side to side. Engaging hips and core muscles is a key element to swimming faster and more efficiently. Great for beginner swimmers; delaying the ball bearing forces exaggerated movements. Prompts a correct stroke rhythm and a symmetrical roll from side to side.