If your dog turns every walk into a tug-of-war, the fix usually isn't more training - it's the wrong equipment. Here's how a collar and a no-pull harness actually compare.
Why collars make pulling worse. A standard collar sits on the neck, so every lunge forward puts pressure directly on the throat. For a dog that already pulls, that's uncomfortable enough to trigger a reflex to pull back even harder against it - which is the opposite of what you want. It's also a genuine safety concern for dogs with a flat face or a smaller trachea.
How a no-pull harness changes the mechanics. A step-in harness redistributes pressure across the chest and shoulders instead of the throat, and the leash clip usually sits at the front of the chest rather than the back. That front clip is the real trick - when the dog pulls forward, it gets gently turned sideways instead of gaining more momentum, which makes pulling far less rewarding without any force or correction involved.
Where a collar still makes sense. For ID tags, a flat collar your dog wears at home all the time is still the standard - it's just not the right tool for walks with a puller. Well-trained dogs that already walk politely on a loose leash do fine on a collar for walks too. The harness is specifically for the pulling problem, not a universal upgrade.
Getting the fit right. A harness that's too loose lets a dog back out of it mid-walk, which defeats the purpose entirely - you should be able to fit two fingers under any strap, no more. Measure your dog's girth before buying rather than guessing a size off their weight alone, since build varies a lot even within the same breed. Reflective stitching is a genuinely useful extra if you're walking early mornings or evenings.