Horizon 637 Lumbar Brace. The Horizon 637 is excellent for post-operative patients in need of lateral support. The addition of moveable, rigid side panels provide lateral support and a comfortable environment for healing. The Horizon 637 provides compression for patients recovering from surgery or injury. The Horizon 637 is one-size adjustable and comfortably fits waists from 24-70 inches, Lateral Extension Panel required for waist size above 50" (Sold Separately) and can be stepped down to the Horizon 631 LSO and also the Horizon PRO for treatment of recurring back conditions.