MediPosture Classic Dental Chair Overlay System, Gray, Single System. Includes: Premium memory foam 3.5" dental headrest, memory foam backrest, knee lift and a 2" thick memory foam chair overlay pad. This four-piece system provides full and comfortable support to areas where patients commonly experience discomfort from factory dental chairs. Cushions are covered with a medical-grade urethane that is designed to withstand disinfection cleanings between patient visits.