Zone 3 Training fins Trail Shoes you still get exceptional lightness you still get exceptional lightness 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 Using fins as part of your swim training can have huge benefits to your overall swim efficiency and speed 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