Different Coil Systems

There are four coil systems commonly found in today's innerspring mattresses: Bonnell, continuous, tied, and Marshall (also called wrapped or pocketed).

Bonnell Coil

The Bonnell coil has an hourglass shape, so the thinner middle part compresses with soft pressure, and the rest of the spring provides deep down support. The Bonnell coil system is the least expensive, and it's also the least durable. This coil system is typically found in the most inexpensive budget mattresses. They make for good dorm or guest room mattresses, but you should look for another coil system for a bed that will get nightly use. A Bonnell coil mattress will only last about three to five years if it's used every night. A mattress with a Bonnell coil is a good choice for children who will outgrow their mattress before the coil loses its supportive qualities.

Inexpensive
Least durable (3-5 years of nightly use)

Continuous Coil

A continuous coil system is made of one single piece of steel that is twisted into individual coils that are connected by helical lacing that runs from the head to the foot of the mattress. The helicals help prevent motion transfer, diminishing the amount of movement you feel from your partner throughout the night. This system is quite durable, and it provides added support in the center third of the mattress, which is where your body needs it most. A continuous coil system is ideal for those who suffer with lower back pain.

Single piece of steel
Quite durable

Tied Coil

A tied coil system is comprised of individual coils that are connected by helical lacing. This design allows the mattress to conform to your body and give a sturdy lumbar support. Tied coil systems provide the stiffest overall support, so they're also a good choice for back pain sufferers. The construction of a tied coil unit makes it quite durable, so these mattresses often come with long warranties. Tied coil systems don't do the best job of reducing motion transfer, so those who sleep with a restless partner will feel movement on their side of the bed.

Sturdy support
Good durability
Poor motion transfer reduction

Marshall Coil

The Marshall coil is a softer, individually wrapped coil system that does a better job of conforming to the body than the other systems. Since each coil is individually wrapped, these mattresses excel in eliminating motion transfer. This also makes the Marshal coil ideal for use with adjustable bases or foundations. Since each spring works independently, this system is slightly less durable than a continuous or tied coil. However, the comfort materials in your mattress will wear quicker than the coil system, so you'll likely move on to another mattress before the system loses its support. The recent dual stage coil-in-coil design, found in Serta Perfect Day and Stearns & Foster Estate mattresses, is an update on the original Marshal coil design, and it includes two separate coils that each work independently to enhance contouring comfort while providing a stiff underlying support.

Good contouring
Good motion transfer reduction
Compatible with adjustable bases
Less durable

Choosing the Right Coil for You

Each coil system has advantages and disadvantages. If you're not sure which coil system is right for you, don't hesitate to call one of our friendly mattress experts who will walk you through the process of picking the right coil (1-800-455-1052).