This strap is used on Levels 2-4. I would highly recommend investing in this so we can do a lot of leg work on the cable machine. These exercises will be great not only for aesthetic reasons, but for physical therapy reasons as well. These exercises will help reduce both back and knee pain. Check to make sure your gym doesn’t have these first, but if they don’t open this up on the device you shop on Amazon with and purchase this. I like these because they stay on the best, and has multiple places for you to attach which is ideal because you will do several different exercises with this.