The Serta Perfect Sleeper Plush 13.5" Hybrid Mattress combines cooling comfort with plush cushioning for restorative sleep night after night. At its core, the Q4 Support System-920 4-in-1 coils with BestEdge foam encasement-provides even weight distribution, stable support, and helps prevent sagging over time. The Zoned Body Support System targets key areas to relieve lower back pressure and promote alignment for all-night comfort. A layer of CushionGel HD Foam enhances airflow and heat dissipation, while memory foam infused with cooling technology provides contouring comfort. EverCool Supreme HD Memory Foam delivers a dynamic combination of cooling and pressure relief for premium comfort. Stay cool and comfortable with a breathable wool layer and CoolFeel Fabric, engineered with advanced cooling performance technologies. The Perfect Sleeper, featuring our Q4 Support System, offers lasting support, pressure relief, and cooling comfort at a great value-for perfect sleep, night after night. Serta StabL-Base 9" foundations provide the perfect support for your Serta mattress and are designed to provide durability and long-lasting comfort. Pairing the matching foundation to your Serta mattress will support it for the life of your mattress and help isolate the effect of your partner’s movements. Serta StabL-Base foundations meet or exceed Federal Fire Retardancy Standards when used with a compatible Serta mattress. Set includes mattress plus box spring/foundation/base. Larger size mattress sets may feature 2-piece side-by-side foundations for easier navigation in tight spaces.