S stands for Speed. Although not a speed rope in the classical sense the dS is fast! And once you've experienced the special swing of the rope, you're hooked. The dS is also the duvide entry model with maximum handling performance due to its vertical and horizontal swivel bearings. In case you own already one of the duvide heavier ropes, you might want the dS as a reserve rope for your travels, office, etc. The price is more than attractive.