The Serta iSeries Hybrid 300 13.5 plush mattress is the ideal combination of spring and foam, soft and cool. This Serta 300 mattress provides luxury comfort at a mid-tier price, with premium pressure relief, support, and cooling technology working together to create the ideal plush sleeping experience. The Serta iSeries 300 mattress is designed for those who like to sleep on their back or on their side, and if you like to shift between the two positions as you sleep, the built-in motion isolation means you won't disturb your partner as you do so. The advanced 886 Pro-Supportâ„¢ Coil System, encased in foam designed to provide edge support, is a solid foundation for the three foam comfort layers that conform to your body as you sleep, providing a comforting hugging feeling while relieving pressure points at the back, shoulders, and hips. Unlike other plush mattresses with a hugging feel, the Serta 300 plush mattress keeps you cool, too, with .5 of Cool ReactionÂ® gel memory foam and 2 of EverCoolÂ® Fuze gel memory foam reducing heat buildup at the sleeping surface. No more sweaty sleep! Try the Serta iSeries Hybrid 300 12.625 plush mattress in your local Mattress Firm store or purchase online to test it out in your home with our 120-night sleep trial today.