CMC ProSeries Aluminum Locking D Carabiners 1". Matching high performance with minimum weight, the CMC ProSeries carabiners are the first aluminum carabiners that meet the NFPA strength requirements. They are the first aluminum carabiners that meet the NFPA strength requirements for General Use. Now with Key-Lock design that helps eliminate snagging when removing from a harness or web. Come in Screw-lock, Manual-Lock and Auto-lock styles