What Is a Martingale 'style' Collar:
A Martingale collar consists of two connected loops
The big loop where the head goes through with an slider to adjust the size &
The smaller loop or “control loop” where there is a d-ring to attach the leash to.
Martingale Collars are useful for training loose leash walking
Martingales are also highly recommended and used by professionals for
improving leash walking and eliminating pulling.

Sometimes it's hard to know what kind of collar would be best for your dog, especially if you've recently welcomed the dog to your family.
The Martingale Collar is a good choice for a variety of dogs because it gives you a little more control than a regular collar plus it has some safety (& health) benefits.
It's often the collar of choice for people whose dog's can slip out of their collars, Dogs can’t slip martingale collars. Which makes them ideal for dog's that are still learning leash manners or who are more likely to pull or wriggle out of their collar aka houdini's.
You can relax as a martingale collar will ensure their safety.
In addition to this regular collars can cause harm to your dog as when the dog pulls on it the pressure is all in one place damaging the dog’s neck & throat. Whereas a martingale collars evenly distributes the pressure which makes it less intense on the dogs neck.
Measurements should take place around the widest part of the head, where the collar slides over when you’re putting on the collar & around the neck, where the martingale will be worn.
Pick the size that fits both of these measurements to ensure the correct fit.
Martingale collars do not have a buckle, to put on the collar it slides over your dog's head.
To wear - The two slides on the small loop should never touch when the dog pulls. This means the collar is too loose and your dog could slip it.