This firm Dortmund Perfect Sleeper® mattress from Serta® features a Custom Support® individually-wrapped coil system and a firm upholstery package with a firm feel. This Serta® Perfect Sleeper® is designed with a unique set of features to help solve five common sleep problems: tossing and turning, lack of support, sleeping too hot or too cold, partner disturbance, and mattress roll-off and sag.