The California King size Serta iComfort Hybrid HB300S Cushion Firm is certainly one of the more interesting models in the line. It offers a wide variety of excellent features at a relatively affordable price, but the medium soft Comfort Scale rating of 6.5 indicates that this mattress feels more like a plush than a cushion firm. In my opinion, this is actually a good thing because it is incredibly adaptable. It is soft enough for side sleepers, but it is still firm enough to provide great support for stomach sleepers and back sleepers.The â€œSâ€� in the name stands for â€œSmooth Topâ€�, which describes the kind of quilt that is incorporated. The quilt is great since it conforms to the body rather well, allowing the comfort layers to do a really good job reducing pressure points. Essential comfort layers include a layer of EverFeel Triple Effects Gel Memory Foam and the signature Cool Action Gel Memory Foam. Both of these high quality memory foams supply exceptional pressure relief to help reduce tossing and turning. The Triple Effects goes a step further by using phase change material to draw body heat away from the surface and help you sleep cooler, and it also uses titanium gel beds to offer added support. The Duel Elite Individually Wrapped Coil Support System is composed of hundreds of dual stage coils that initially conform to the body and then provide solid underlying support. This system is especially beneficial for couples since it helps minimize transfer of motion, so you sleep undisturbed, and is also compatible with an adjustable base. The Best Edge Foam Encased edge support ensures freedom of movement, even when sleeping at the edge.To sum up, the California King size Serta iComfort Hybrid HB300S is an excellent mattress for just about everyone, and it is one of my personal favorites this year. Its combination of support, comfort, and value make it a great choice. Product info furnished by Carolina Rustica.