DMM Ultra O Durolock Carabiner

The DMM Ultra O is a large oval carabiner, and this version has the Durolock auto-locking gate. Arborists use the Ultra O where they need room for several pieces of hardware and want them to sit centered.

Where the Ultra O fits

Ovals keep whatever you clip centered between the two ends, and the Ultra O gives you more room inside than a standard oval. That extra space helps when you are stacking a pulley, a rope grab, and a sling in one connector, or clipping thick webbing.

Climbers use it for pulley-based hitch tending, SRS anchor setups, and as a connector on rigging gear. The Durolock gate is an auto-locking design that closes and locks on its own. Check the strength figures on the spine before using it in a life-support system.

Inspection and retirement

Before each climb, open the gate and let it snap shut. It should close fully and lock on its own without sticking. Look for cracks, sharp edges, grooves worn by rope, and deformation at the nose or hinge. Sap and grit are the usual cause of a lazy gate, so rinse and dry the carabiner and keep the gate mechanism clean.

Retire any carabiner that has been dropped from height onto a hard surface, shock loaded, or shows wear you cannot explain. Read the markings on the spine and confirm they meet what your system needs. Life-support gear must meet the applicable standard (ANSI Z133 and the manufacturer's instructions), be inspected before every climb, and be used only by trained climbers. See more auto-locking carabiners.