I have been using swim cord bands as additional swim training for personal training and coaching. However, since Covid hit and forced lockdowns, I have been looking for swim specific training tool in the market as the swim cord approach has, unfortunately, had multiple gaps:
I find that core engagement and streamlined horizontal positioning are neglected. So then the next solution is combining the swim cord and a bench or yoga ball; the next challenge that occurs with the bench plus cords compo is that the bench is a stable platform, and it's hard to engage the core facing down a stable platform. Finally, the yoga ball is unstable. However, you are in a streamlined horizontal position.
The zen8 swim bench plus the swim cord checks both core engagement and streamlined horizontal position concerns. It is imbalanced, activating my core while on it and firing up every muscle for a better-streamlined horizontal position with every stroke.