It can be employed both amongst the knees for aspect sleeping or guiding the knees for back sleeping. For a facet sleeper, I kept it in between my knees and found that it stayed put better than a memory foam knee pillow. "Very affordable knee pillow having a double-layered foam https://zenblok.com/products/leg-elevation-bolster-back-relaxation-wedge-knee-pillow-for-leg-and-back-pain-large-11-inch