Opera beds. The Gel Pro 4000 is the ultimate hybrid adjustable mattress with a pocket count of 4000 and multiple layers of foams. The high-tech hybrid composition combines 1000 nested pocket springs with layered gel-infused foams and a 3000 pocket surface gel matrix that has both cooling and pressure relieving properties. The mattress is firm and supportive whilst specially designed to conform to the adjustable base of an Opera bed. Stitched carry handles mean the mattress can be maneuvered on the bed and a ventilated top cover facilitates consistent airflow to prevent heat and moisture build up.