I have fibromyalgia and have had horrible lower back muscle spasms for years that not even muscle relaxers and pain killers will help. The other day, I was having a terrible spasm, but using the Back Wave II for just five minutes made me feel 100% better. I’ve only used it several times, but I feel like it’s already paid for itself! I strongly recommend it, even if you don’t have muscle spasms – it’s a great way to relax your back.