The Spire is 361 luxury model, and it delivered the highest heel-cushioning scores of any shoe in this guide. That cushioning comes from a midsole made from layers of different materials and densities. Directly under the foot, the insole and top layer of the midsole are molded with rubber-infused Quickfoam for a soft, cushioned feel. A slightly denser, traditional foam forms the lower layer of the midsole under the heel and on tie inside of the forefoot. Some loved the foot-coddling.