Knuckle of using oil quenching process, the hook claw reached the highest level of soft hardness (maximum hardness of 39), play the steel in extreme operating conditions reliability.Hand-forged hook shank ring shaped into a circle, but also oil quenching process using soft steel rims so that both, the latest design tetradentate fold increase carabiner Rims bold to 8MM, loading capacity of 400 kg.Four paws alone can expand or collapse, also convenient to carry.