The Harvest Mattresses all feature our very own advanced pressure-relief support system. These units are manufactured by us first hand in our own Factory in Chicago, IL. This unit offers a strategic arrangement of coils placed in distinct zones for proper support at the same time eliminates any feeling of "roll-off" towards the sides. All coils are wrapped in a food-grade polypropylene fabric which is non-woven and non-toxic. All coils float individually for proper spinal alignment as well as to promote better airflow for cooler sleep. The springs are constructed from 2 different wire gauges; 15 gauge (narrow diameter) through out the center; 13 3/4 gauge (thicker gauge) on both sides of the mattress. Our upcycled steel units afford our mattress the ability to deliver the very best in edge support throughout the life of the mattress and truly support our Customers in need of pressure-point relief. The use of heavier gauge wire in our construction provides a more supportive surface.