If you are recovering from a below-the-knee injury or surgery, the 990X all-terrain knee walker by Drive Medical is an excellent pain free alternative to crutches and designed to keep you active. The rugged, steel frame and four large, all terrain traction tires are designed to never go flat providing extreme stability when used indoor or outdoor making maneuverability over gravel, dirt, grass, mulch, gaps on the sidewalk, doorway thresholds and uneven pavement easy. Fully adjustable to meet you