Without question this is the most popular of all the aluminum carabiners manufactured by SMC. With a timeless design, the SMC NFPA Aluminum Locking D is widely accepted as the de facto standard for mountain and urban rescue applications as well as by an ever-increasing number of work-safety and industrial users. All this is due in part to its high strength, light weight, wide gate opening and functional versatility. Note that the nut of the locking sleeve engages on the gate, not on the carabiner frame, this helps prevent jamming or vibrating loose a benefit not to be overlooked. Through continuous inspection throughout production, careful attention to detail and precision craftsmanship we consistently manufacture product at the highest levels of quality.