3/16″ neoprene covered aluminum hinged stays have hyperextension stop at 170°, one each medial and lateral. Universal buttress pad of felt attaches with hook to provide lateral, medial, inferior or superior patellar support. Opposing loop-lock straps above and below patella, 12 1/2″ long. Specify size (knee circumference) Small 13″-14″; Medium 14″-15″; Large 15″-17″; X-Large 17″-19″.