SMC Large Ss Sg Black. The Large Steel Locking D was developed especially for the needs of the fire and rescue communities with a large gate opening that easily fits over litter rails. The NFPA21001 & NFPA21007 are the models that are stamped with the requisite UL Certification. The components used in this carabiner are meticulously hand-finished prior to final assembly resulting in the smooth free gate action that is the hallmark of all SMC carabiners. The sleeve locks on the gate rather than the body of the carabiner eliminating problems of the knob binding on the frame after the carabiner has been loaded. Utilizes stainless steel gates and locking sleeves for smooth action greater strength and optimal reliability. Additionally each carabiner is 100percent hand-inspected for gate action and other functional characteristics before leaving our factory. Package Contents: SMC Large Steel Carabiners