I’m very happy with my new 12’ Serta Hybrid mattress. I was looking for a firm comfortable mattress and this cooling hybrid is definitely perfect for my back sleeping. No more sleepless nights. I love the design, and the dark blue color for not viewing any staining. This cool twist gel memory mattress is very comfortable, not too firm with a great support and I can sleep all night without having any back pain or discomfort. My favorite  is the 3 zone coil design system. Good quality mattress. Highly recommend it for everyone .