Comfort Clinic 3-Inch VE Memory Foam Mattress Topper, King For improved sleeping comfort, 3-inch visco elastic memory foam topper for king bed; great alternative to mattress purchase In 100-percent polyurethane, hypoallergenic memory foam with 2-1/2-pound density Responds to sleeper's weight and body temperature, molding to personal contours; reduced size for better fit under sheets After unpacking, allow up to 72 hours for topper to fully expand; available in other thicknesses and mattress sizes Measures 77 inches long by 74 inches wide by 3 inches high