The 8. 9 Dry Climbing Rope is Black Diamond's skinniest single rope and the fattest twin rope, making it incredibly versatile for sport crags, alpine routes, and everything in between. It's Black Diamond's only rope certified as a twin, half, and single rope. This version features a dry treatment that's been certified by the UIAA for eliminated water absorption, and the treatment also helps the sheathe resist abrasion if you climb more rock than ice.