Zone 3 Training fins Trail Shoes Solid foam with textured service Solid foam with textured service the upper offers Altras unique footshape technology that allows the toes to be relaxed and allows them to spread out naturally with the big toe remaining in a straight position for additional comfort By using these fins as part of your kick and swim sets you will automatically get the feeling of how your feet should be positioned when swimming unassisted and over time your ankle flexibility and leg strength will improve Many developing swimmers underestimate how important the kick is to the overall body position and speed through the water