The Tremor is an all-terrain beach and snow wheelchair designed for individuals with mobility or lower extremity disabilities or spinal cord injury. FRAME: Ultra-lightweight, fully-adjustable frame. Anti-tips are optional. The frame is available in a variety of colors and patterns. Frame protectors are optional. SEAT (WxD): 14, 15, 16, 17, or 18 inches x 12, 13, 14, 15, or 16 inches are standard. Seat depths of 10, 11, 17, or 18 inches are available at an extra cost. Push handles, seat belt, and side guards are optional. UPHOLSTERY: The standard upholstery is black adjustable. Red or blue upholstery is optional. CUSHIONS: Optional cushions are available. ARMRESTS: None. WHEELS: 24 x 4 inch all-terrain Fatso balloon tires with aluminum rims and big-button quick release axles are standard. A variety of optional wheels and tires is available. Anodized black handrims are standard. Vinyl-coated and Natural-Fit handrims are optional. CASTERS: 8 x 2 inch Fatso balloon tire casters. FOOTRESTS: Single loop adjustable footrest (with riser if necessary) is standard; single flip-back, single loop (no riser available) is optional. A calf strap is optional.