Thermoskin knee wrap combines heat therapy with gentle compression to offer relief from arthritic knee pain, fluid in the joint or swollen, aching knees. Helps increase blood flow to the joint. Fits left or right knee. Hook-and-loop closure is easy to put on and remove. Measure beneath kneecap when knee is slightly bent: Medium (13.25"-14.5"), Large (14.5"-15.75"), XL (15.75"-17"), XXL (17"-18.25").