Passion is from the Perfect Sleeper collection. The spring system used is called the Posture Spiral spring system, patented by Serta. This spring system is fully heat treated, has continous coils and have helical wires running from head to toe and minimises partner disturbances.It also features ACQ (Advanced Comfort Quilt).The ACQ technology benefits the customer through its unique feel and comfort level. The ACQ technical research focuses on the quilting since the body comes into contact with the quilted panel which is the surface of the mattress.The ACQ Technology blends in sophisticated convoluted layers of quilting to the mattress, creating specialized comfort zones. Each of these quilted types has a relatively denser zone in the centre one-third, providing additional support to the spine. Lush layers of polyester wadding passes through the Foam convolutions to provide supreme comfort. The ACQ layers are unique for the plush, luxurious feeling and breathability. Also, convoluted foam layer provides breathable air pockets which further enhances the feel. This is a two sided mattress which is turnable and is about 10 inches high.