* Provides additional support & stability for the medial lateral ligaments.* Its 2 hook & loop straps allow adjustment for a better fit.* The additional neoprene circle pad around the patella provides padded protection and stabilisation to prevent patellar displacement.Measure around mid-section of the knee while in a standing position11-12(1/2)" - 27.9-31.8cm - X-small13-14(1/2)" - 33-36.8cm - Small15-16" - 38-40.6cm - Medium16-17(1/2)" - 40.6-44.4cm - Large18-20" - 45.7-50.8cm - X-Large