The DonJoy Knee Brace Undersleeve is designed with a closed patella (kneecap) and increases comfort by protecting your skin; minimizing chaffing from the brace, reducing abrasion and preventing rashes. Using this undersleeve is a great way to keep your leg and knee a bit warmer during cooler months, while helping to control moisture during warmer times. It's easy to apply, especially for those with arthritis; and the tapered design reduces migration without the use of rubber, latex or elastic bands. The machine washable undersleeve is made of 85% cotton/15% lycra. Undersleeve can be worn with or without a knee brace (brace sold separately). Universal fit allows the DonJoy Knee Brace Undersleeve to be worn on either the left or right leg.