Basyx VL504SP11 VL504 Series Mid-Back Knee-Tilt Chair with Black Leather Upholstery Luxurious leather upholstery over a durable textured steel frame. Contoured back with lumbar support for all-day comfort. Cantilevered arms provide enhanced side-to-side movement. Five-star base with casters for easy mobility. Preassembled components assemble with only three screws.