Knee Immobilizer, 16" (3216)White cotton sateen on 3 8" thick foam, nylon tricot lined. One each medial and lateral stays and two contoured posterior stays are removable. Alternating loop lock straps close with hook and loop. Two adhesive foam strips and popliteal pad included. Specify size Small upper 15" 18" lower 9 3 4" 12 3 4"; Medium upper 17 3 4" 20 3 4" lower 12 1 2" 15 1 2"; Large upper 20 1 2" 23 1 2" lower 15 1 4" 18 1 4"; X Large upper 23 1 4" 26 1 4" lower 18" 21".