Many of the gadgets sold in pet stores are designed to appeal to human ignorance about dogs, not to help dogs.
Dog harness' fall squarely in that category.
People generally buy a dog a harness because their dog is pulling on the leash.
But before you waste your money on this useless device, stop and think like a dog.
for a moment.
The harness was invented by some brilliant person many centuries ago.
It was designed as a practical way to help and encourage animals to pull loads.
This invention has benefited humanity over centuries of good use before the advent of internal combustion engines.
The inventor is to be lauded.
However, you want your dog to walk politely not to pull.
Why would put a device on your dog that is specifically designed for and encourages him to pull? As a professional dog trainer, I do not allow my clients to use harness devices.
The best way to train a dog is with a collar.
A collar mimics a bite on the neck which is universally understood by dogs as a communication to cease and desist whatever behavior they are engaging in.
In other words, they understand a properly timed tug on the neck.
That's what bitches do with their puppies and the puppies understand by instinct.
A harness by means of the increased leverage it provides you, may cause your dog to walk closer to you.
But dog training is about training your dog what you want rather than to merely display that you are the strongest.
If you want to learn how to teach your dog to heel then use the proper tools.
Forget about the harness unless your intent is for your dog to pull a sled or you.