Features The DonJoy Reaction Knee Undersleeve replacement is made of 85% nylon/15% spandex Compatible with the DonJoy Reaction WEB and the DonJoy OA Reaction WEB knee braces When used, helps extend the life your knee brace DonJoy Reaction Compression Support: Knee Brace Undersleeve, Medium Description The DonJoy Reaction Knee Undersleeve replacement is made of 85% nylon/15% spandex. Compatible with the DonJoy Reaction WEB and the DonJoy OA Reaction WEB knee braces. To ensure a proper fit, take the measurement of your thigh and calf, 6 inches above and below your kneecap using a flexible type tape measure. Use the circumference you measure to choose your size. The DonJoy Reaction Undersleeve runs small. Should you measure between sizes, we recommend going up one size for optimum comfort and fit. About Us Since our founding, we have taken special pride and pleasure in being able to participate in the exciting world of eCommerce and providing products of the highest quality. It is with this philosophy that we want to run our store and provide exceptional value to you as our customer. Payment We accept payment by PayPal. Tracking Your Order: Once your order ships a tracking number will be sent to you via the email address used to place your order. Problem with My Order: For concerns regarding your order, please contact us here. Shipping All of our shipments are free for you our customer unless you decide to upgrade your shipping for a small fee. At this time we only ship to the continental 48 states of the United States. We do not ship to PO/APO boxes. Returns Returns can only be requested within 30 days of the product shipment date. We offer free return shipping for all of our items. Returned items must be in their original packaging with everything included. Please contact us here (link) for help or assistance in processing a return.