The Petzl Zephyr is the toughest all-around rope in their line. The 10.3 mm diameter offers additional friction in belay/rappel devices for more control, and is extra durable. This workhorse rope is great for people just getting into the sport or for those who want the increased longevity of a thicker diameter rope. Specs: Certification: CE/UIAA Diameter: 10.3 mm Type: Single Rope Weight: 67 g/m UIAA falls: 10 Impact Force: 7.28 kN Dynamic Elongation: 33.7 % Static Elongation: 6 % Sheath %: 34