Support Your Body
Support Your Body

Correct support is an essential ingredient for a healthy body. It is mainly delivered through the “core” of the mattress, which can be innerspring, foam, air or water. It is also delivered through the box spring or foundation under the mattress.

A good mattress and box spring will gently support your body at all points and keep your spine in the same shape as a person with good standing posture. When trying a mattress, pay special attention to the heaviest parts of your body; your hips, shoulders and lower back.  If there is inadequate support, you may develop back pain. However, if a mattress is too rigid, you may experience uncomfortable pressure.

Innerspring mattress layers from Original Mattress Factory


Innersprings are the most common type of support system used to make mattresses. These units are comprised of metal coils that are either pocketed or open and laced. Innersprings conform to and support your body by allowing your hips and shoulders to penetrate the surface while allowing the back to be supported in its proper position.

When shopping for an innerspring mattress, there are a few things to consider:

1 - Coil Count:

The number of coils in the unit. Counts are usually quoted in full or queen sizes. The number of coils alone has little bearing on the quality of the unit. The coil design, wire gauge and number of turns must also be considered!

TIP: Pay attention to the number of coils in your mattress! Coil count is not everything, but there should be more than 300 coils with a minimum of 13 gauge wire in the full size model.  Likewise, there should be a minimum of 375 coils, 13 gauge wire in a queen size, and 450 coils, 13 gauge wire in a king size.

2 - Wire Gauge:

The thickness of a wire. The lower the number, the thicker and more durable the wire. For example, a 12 ¾ gauge wire is thicker than a 15 gauge wire.


Innerspring Coil Count from Original Mattress Factory
Coil Count

3 - Number of Turns or Rotations:

A coil turn is defined as a complete rotation in the coil. More turns equates to more coil resiliency and longer coil life. In addition, more turns allow the sleeper’s weight to be distributed across more wire, resulting in less wire fatigue in the coil.

4 - Unit Size:

An innerspring unit can be standard size or foam encased. In the former, the coils extend from edge to edge, providing uniform support. Some standard size units also have a border rod around the perimeter for additional edge support. In a foam encased unit, which is smaller in size, coils are removed and replaced with a foam edge. All innerspring units used by The Original Mattress Factory are standard size units with a border rod construction.

Border Rod additional mattress edge support from Original Mattress Factory
Border Rod
Foam Encasement on mattress from Original Mattress Factory
Foam Encasement

5 - Design of the Coil:

There are five basic types of innerspring coil designs: Marshall, Bonnell, LFK, Offset and Continuous.

Marshall coil innerspring from Original Mattress Factory
Marshall Coil

Marshall Coil A straight barrel, unknotted coil that is encased in fabric.  It is sometimes made with non-tempered steel, which reduces the long term resiliency of the springs.  (Also known as a pocketed coil.)

Tempering: Tempered innersprings are stronger, more resilient and therefore more durable.  The tempering process, which involves heating the wire or innerspring unit to a high temperature, can be done electronically or in a tempering oven.  The term “double tempered” or “twice tempered” is often used in the industry, but once a coil has been heated to the optimum temperature to achieve tempering, it cannot be tempered twice.  All coils used by The Original Mattress Factory are tempered for maximum durability.

Bonnell coil innerspring from Original Mattress Factory
Bonnell Coil

Bonnell Coil - An hourglass shaped coil with a round, knotted head.  It is made with tempered steel and is commonly used in most national brand entry level products as well as some promotional products. The Bonnell coil unit is used in The Original Mattress Factory’s Classic mattresses.

LFK coil innerspring from Original Mattress Factory
LFK Coil

LFK Coil - A straight barrel coil with an offset, squared and unknotted head. It is made with tempered steel and is a premium innerspring unit utilized in the flagship product lines of several brands. The LFK coil unit is used in The Original Mattress Factory’s Regency Sapphire mattresses.

Knotted Offset coil innerspring from Original Mattress Factory
Knotted Coil

Offset Coil - An hourglass shaped coil with a square head that can be knotted (as shown below) or unknotted.  It is made of tempered steel and is used in premium quality innerspring units found in high end luxury brands. Our best Offset knotted coil unit is used in The Original Mattress Factory’s Orthopedic mattresses.

Knotted Coils: The end of a coil is either knotted or unknotted. Knotting utilizes more steel and gives the coil more stability.

Continuous coil innerspring from Original Mattress Factory
Continuous Coil

Continuous Coil - A strip of coils that runs either vertically or horizontally with each head representing the end and beginning of consecutive coils.  It is made of one piece of tempered wire and commonly has a high coil count, but uses less steel and a much thinner gauge of wire with a low number of turns.