French Martingales are a combination of a collar and a leash into one! They use a cinch closure to manually tighten or loosen around your dog's neck. This is not an automatic via leash tension cinch like a standard martingale or limited slip, it requires the handler to slide it open or closed. These collar/leash combos are *excellent* for agility performances or sports where the dog must run naked, as they are quick to remove and quick to put on. I do not recommend these for lure coursing unless you are good at wrangling your dog's head when they're staring at the bunny.