Many new models of both, innerspring and hybrid mattresses, feature Micro/Mini Coils – recent development in coil design. In this new technology by coil manufacturers, mattresses feature layers that contain coils as short as 2" (sometimes shorter). More often, these mini/micro coils are individually pocketed and they fit in thousands in one layer. They are not necessarily used in main support layer of the mattress, but are also used as part of comfort layers, with some models having several micro/mini coil layers. These micro/mini coil layers are not only used for support, but they are also used for ventilation/cooling, surface smoothing, and firmness adjustment.