Between knee foam pillow (Western Dearborn)

This small foam device is made to go between your knees to hold your legs in the proper position to help with back pain. This is for a side sleeper. I got it for my husband and he won't use it. It cost almost $50 and I bought 2 extra zipper covers for it. It was advertised as being one of the best made pillows for alignment for your hips. I think it might take some time to get used to it and then you can't sleep w/o it!