iSeries NXG - 13.5" Memory Foam Ultra Plush Mattress 4500Weve evolved the Serta iSeries NXG to be the next generation of comfort. We've built this Ultra Plush feel mattress with a series of benefits for the sleep you want. Experience immediate cooling, instant pressure relief, and ideal support for a deeper , more restful sleep at a price that makes sense. Featuring high density memory foam, NXG Memory Foam delivers deep, contouring pressure relief. A cool to the touch fabric oers instant cooling, while