Not one layer of springing but two in the luxurious Duo comfort. To ensure the most restful night's sleep Sleepvendor have built a double layer of springing in the mattress. Multiple layers of superior fillings combine with the springing to give the gentle firm support that Duocomfort provides. · twin 13.5 gauge double heat treated open type spring · flag stitched handles for ease of turning · vents to allow the mattress to breathe · Multiple layers of high grade filling materials · luxurious deep quilted finish