iSeries NXG - 13.5" Hybrid Firm Mattress 3500Weve evolved the Serta iSeries NXG to be the next generation of comfort. Weve built this Firm 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 Carbon