What is the Mc David Ligament Knee Support? Improves knee stability during sports following cartilage, medial (inside) & lateral (outside) ligament injuries. Two horseshoe buttresses, two medial & two lateral stays, plus an open kneecap provide support & ventilation without the restriction of a metal hinge. When can I use it? Ideal for improving knee stability following medial (inside) or lateral (outside) knee ligament injuries. Provides stability, support & reassurance following knee cartilage injuries. What size is it? Fits left or right knee. If you are between sizes, please choose the larger size. Measure round the knee: Small 30-35cm (11¾"-13¾") Medium 35-38cm (13¾"-15") Large 38-43cm (15"-17") X-Large 43-50cm (17"-19¾") XX-Large 50-56cm (19¾"-22") How does it work? The Mc David Ligament Knee Support offers enhanced knee stability owing to the support provided by superior horseshoe buttresses, along with medial & lateral stays that reinforce the brace on either side of the knee joint. Held firmly in place by two Velcro straps & four elastic crossing straps, the knee supports 4mm Neoprene fabric offers a superior combination of support, compression & heat retention, which eases knee pain & swelling around the knee.