Use a soft tape around the neck where the collar will sit, keeping the tape snug but not tight. Compare that measurement with the product's stated adjustable range.

A posture collar is wider or more rigid and limits head and neck movement. A standard collar is usually more flexible and better suited to longer wear.

It should feel secure without affecting breathing or swallowing. Check the manufacturer's fit guidance and monitor comfort throughout use.

Not unless the product is explicitly designed and rated for suspension or load-bearing use. Decorative rings and leash hardware should not be assumed to support body weight.