My obgyn prescribed me one. It's called a prenatal cradle. I love it. It took me a little too get used to, but it's amazing. They really do help with pain.
My mom bought me one that a friend of ours had in her garage sale, I never used it with my 2 previous pregnancies but I hurt myself at work lifting and she said it would help keep support off my back I haven't used it yet I'm not that big yet only 16 weeks but will definitely be using it.