Nite-Ize CSL4-01-R6 Carabiner Slidelock Steel #4

This carabiner is designed with an innovative slide-to-lock feature that securely locks the gate with a simple push and slide movement, and unlocks when you want it to just as easily. Then, instead of a bulky tubular construction, they designed a cross sectioned, rectangular stainless steel body that's durable, low profile, and slim so it feeds more easily through smaller openings and rests flat in pockets.