The Saatva HD mattress is constructed with a single layer of offset coils. Like traditional mattress coils, these are shaped like an hourglass, but the bottom is slightly offset. That creates a hinging effect when the coil is compressed, making them better able to conform to the body's curves.
The Saatva HD coil unit is made with 12.5-gauge tempered steel, the strongest in the industry, for maximum durability and resistance to sagging. The coils are then threaded with a 17-gauge helical wire for added contouring ability and reduced motion transfer.