Sterling Rope aluminum carabiners all use high quality 7075-T6 Aluminum for the frames and sleeves. Key lock design prevents the nose and sleeve from snagging on gear. The sleeves are precision manufactured for consistent and smooth action during operation. All carabiners are proof-loaded and individually inspected to ensure high strength, top notch quality, and superb gate and sleeve action. Manufactured in USA. The SR Steel is a high strength carabiner for technical rescue and industrial applications where high loads are expected. The SR Steel features a key lock design and has a wide gate opening for stacking multiple ropes or slings. Manufactured in USA and certified to NFPA 1983 General-Use.