Mueller Sport Care Elastic Knee Stabilizer brace.  Size L/XL.  Brand new in package - I just bought the wrong size.  Includes one brace that can be used on either the right or left knee. 

Features:

- Lightweight, breathable fabric helps provide comfortable support without reducing mobility. 

- Firm side support from 4 supportive steel springs

- Moderate support level

Measuring around center of knee, this fits knees 16-20 inches/30-40cm.