A comfortable viscoelastic “memory foam” top molds to the anatomically shaped, round-edged pocket below in the high density bottom. Pocket reduces pressure on ischials and coccyx. Bottom layer is contoured to encourage healthy, upright posture and proper positioning of the legs. Cover consists of anti-slip top surface and non-skid bottom. Built-in sleeve in bottom of cover allows use of molded Sling-Fill base; 18-month warranty.