The Osteoarthritis Night Time Knee Pad / Side Sleeper Pad is made with a soft, breathable elastic sleeve that has a 1 1/2 inch thick pad sewn into the inside of it. The pad is specially cut to fit gently between the knees and provide cushioning for aching knees. The benefit to the Osteoarthritis Night Time Knee Pad / Side Sleeper Pad rather than a pillow is it stays in place throughout the night regardless of movement or even getting out of bed. If you are looking for night time knee pain relief, improved hip or spine alignment we encourage you to give alphabrace.com"s Osteoarthritis Night Time Knee Pad / Side Sleeper Pad a try. Size Guide Measure around the leg 5.5 inches above the center of the knee cap. Small 13.5-16" 34cm-40cm Medium 16.5-18.5" 41cm-47cm Large 19"-22.5" 48cm-57cm X-Large 23"-26" 58cm-66cm