Our Spring down cushion is extremely comfortable and supportive and is the standard seat on most Michael Thomas styles. It is also available as an upgrade on many styles. The springs are made of high quality carbon steel, and each coil is individually pocketed. The coils are then encased in 1.8 density polyurethane foam. The foam is then wrapped in a blanket of down feather and placed into a down proof ticking. Our spring down cushion carries a limited lifetime warranty.