Recommended by Judo Therapists: Knee Support Easy to put on and take off, full-open type Special spring Mesh material V-shaped belt EVA cushion Size L Measure the circumference of your thigh 10cm above your knee. If your thigh circumference is 46-55cm, size L is recommended. My thigh measured about 48cm, so I bought L, but it felt a little big, so I'm currently using size M. I am a 177cm, 70kg man of average build, and my legs aren't particularly thick, but size M fit perfectly. I think this size L would be suitable for those with slightly thicker thighs. I only tried it on and haven't used it. I exchanged it for size M, so please do not request a size exchange from the manufacturer.