The DonJoy Neoprene Knee Brace Undersleeve is designed with an open 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. Made of top quality perforated neoprene, and is machine washable. Undersleeve can be worn with or without a knee brace (brace sold separately). Universal fit allows the DonJoy Neoprene Knee Brace Undersleeve to be worn on either the left or right leg.