DMM Ultra O Durolock

The DMM Ultra O Durolock is an ultra-light and extremely strong carabiner with a patented auto-locking **Durolock** gate that requires four separate movements to open. It offers maximum security in complex rigging systems, arborist work, and high-altitude operations.

The Ultra O series from DMM is one of the most popular carabiners worldwide thanks to its high strength-to-weight ratio, ergonomic feel, and ability to keep system components in perfect alignment. The deep, symmetrical oval shape (**O-shape**) allows slings, ropes, pulleys, and other carabiners to center naturally under load, while also allowing easy stacking of components on both sides. This makes it ideal for arborists in both basic and advanced systems, such as with triple-load pulleys.

The Durolock system is DMM's most secure auto-lock: it requires four distinct movements to open the gate, minimizing the risk of accidental opening in dynamic environments with moving ropes. The gate is still easy to operate with one hand. Made in Wales from hot-forged and heat-treated aluminum with an I-beam construction for optimal strength and low weight. The Keylock nose prevents snagging on ropes and harnesses.

Features

• Durolock auto-lock: Four-step opening mechanism for the highest security against accidental opening[1][4].
• Oval symmetrical basket: Provides natural centering of blocks, ropes, and harnesses for stable loading[2][3].
• I-beam design: Maximum strength-to-weight ratio with ultra-light construction[3].
• Clean nose Keylock: Snag-free connection without the risk of hanging in ropes or equipment[3].
• Ergonomic: Feels good in the hand and is easy to use in complex rigging[1].
• Two-finger grip: Comfortable handling even with gloves[1].
• Corrosion protected: Anodized according to BS12373-2001 Class 10E1[3].

Technical Specifications

• Color: Titanium/Purple
• MBS Major Axis: 25 kN
• MBS Minor Axis: 12 kN
• MBS Gate Open: 7 kN
• Gate Opening: 19 mm
• Dimensions: 63 x 109 mm
• Weight: 74 g
• Material: Aluminum, hot-forged
• Certification: EN 362:2004 B, EN 12275:2013 H
• Article number: A324
• Country of manufacture: United Kingdom (Wales)

Perfect for arborists, rope access technicians, and climbers who demand reliable performance in challenging environments.