What is zoned comfort? With alternating levels of firmness, ergonomically design support zones in every Serta mattress are designed to keep your body aligned as you sleep. 5 Support Zones: Designed to keep you in natural alignment throughout the night. Providing enhanced support where the body naturally curves (lower back, upper thigh) and ensuring comfort where the body touches the mattress the most (shoulders, hips, lower legs). Ideal for back and side sleepers or those who change positions throughout the night. * Serta iComfort Foam: Features zoned support from memory foam layers for contouring pressure-relief and breathability