I love this roller. The 18 inches is a perfect length. The foam is the right density. This is a great tool for anyone in chronic pain.
If you are not familiar with foam rollers, there are a bunch of helpful videos on you tube that can show you how to use them. You can also ask a trainer at your gym to show you how to use them. They are a great way to address muscle tension and pain.
I won’t lie, there is a learning curve to these. When I first started using them I felt like I was just flopping around on the floor, but with practice I was able to figure out what was helpful for me. The biggest benefit to a foam roller is that they are really low risk. It is unlikely that you will have any harm come from trying one of these out. And for many they are very helpful.