I purchased this harness for a rescue dog that is very much afraid of the world, and was an escape risk, showing the ability to back out of other harnesses. The harness fits very well, is easy to adjust, and she definitely cannot get out of it. I think the good fit actually calms her, sort of like, but not as snug as, a 'thunder jacket.' I also want to mention that I have another Ruffwear harness that's 8 years old for my other dog! These are super sturdy, well made, and function great :)