I suffer from lower back pain and both my chiropractor and PT recommended that I use these rolls for my car and for the chair at my desk. I have to say that this has helped tremendously. The strap helps the roll stay in place. I have had mine for over 5 months now and it still works fine. The one in my car has been there for over 3 months and is still in good shape as well.
Some reviewers have recommended using other objects, such as rolled up towels or sweats, in place of this lumbar roll. I have also used a towel, but I find that this roll stays in place much better and provides a uniform/consistent level of pressure along the roll. The downside is that after a few months of usage, the foam no longer feels as firm. It still works fine, but I can see that maybe another year down the road, I may need a replacement to give me the firmness that is helpful.
I also have a blow-up version that I use on planes. That is also very helpful and makes medium to long flights (3+ hours) much more comfortable.