What is the Mueller Adjustable Elbow Support? Adjustable elbow support for the relief & treatment of elbow pain & elbow injury. When can I use it? For relief of elbow pain, including tennis elbow Ideal to aid healing of elbow injuries. Great for use in cold weather. Which size do I need? Fits right or left elbow. One size fits most. How does it work? The Mueller Adjustable Elbow Support provides protection & support to a sore, weak or injured elbow. Its slip-on design & adjustable straps make it easy to apply & tighten, thus helping to relieve elbow pain & the symptoms of elbow injuries, including elbow arthritis.