These mattresses feature a single length of wire in each row or lattice. Each wire is shaped into a coil and interlaced to the top and bottom of the spring frame. The coil is made from strong wire that can vary in thickness. If the wire is thicker, the mattress is firmer. If the wire is thinner, the mattress is less firm. This design limits the amount of movement across the mattress so may help reduce partner disturbance.