10 Year Warranty

A great addition to the "Comfortec" line, the Double-Sided "Shelton Firm" boasts a coil unit that's exclusive to Symbol Mattress. The "Spectrum 540 3-Zone" is somewhat of a breakthrough in the sleep products industry!

The open coil design is made to be soft on the surface but it progressively firms up as weight is applied to it. This offset spring design contours very well to your body and adds some durability to the mattress. Symbol has also put 30% more coils into the lumbar region for added support - where you need it the most. Additionally, the longitudinal helical lacing helps to cut down on motion transfer - so if your partner gets up or moves around a lot, you likely won't feel it.

With all of the great technology inside of the Shelton, it isn't overdone with fancy-named features or useless (extra) layers of foam. This mattress is more the "old school" type of product and feel. It's reasonably simple in design, with emphasis on quality craftsmanship and it harkens back to when mattresses lasted much longer and cost less.

Firm in feel but with enough body contouring coming from the spring unit - and just enough high-quality comfort foam layers - this model is sure to become one of the most popular mattresses at Michigan Discount Mattress. Call to see if we've got it in stock today!

Width: Length:

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Double Sided Firm Shelton

This mattress can only be made in standard sizes. To see prices, please click here

Mattress Scale
semi firm mattress
Approx. Height of Mattress: 11"

This Mattress Features:

CertiPUR-US certified foams are:


✓ Made without ozone depleters
✓ Made without PBDEs, TDCPP or TCEP (”Tris”) flame retardants
✓ Made without mercury, lead, and other heavy metals
✓ Made without formaldehyde
✓ Low VOC (Volatile Organic Compound) emissions for indoor air quality (less than 0.5 parts per million)
✓ Made without phthalates regulated by the Consumer Product Safety Commission


Natural Cotton Cover
FR Barrier
Comfort Foam
Firm Quilt Foam

Mattress(Top Side)
Convoluted Comfort Layer

540 Tri Zoned Spectrum® Coil, Foam Encased

Mattress(Bottom Side)
Convoluted Comfort Layer

Firm Quilt Foam
Comfort Foam
FR Barrier
Natural Cotton Cover


10 Total Years (10 full)

Double Sided Firm Shelton

For years, our "old reliable" mattress model was the "Franklin Firm". It was available in custom sizes, it could be made with a double-sided design (so that it could be flipped) and it was composed of high density foams and a strudy coil unit. This is one of the rare times in which something very good was replaced by something great: enter the Double-Sided "Shelton Firm"...

The 540 "Spectrum" VertiCoil design is a Symbol-only exclusive that offers more comfort than the Bonnell Unit that was in the Franklin and, it's quite durable as well. There is even a greater coil density in the middle-third of the mattress - the lumbar region - than in the rest of the bed. The style of spring attachment uses "Helical Lacing Wire" which helps to cut down on partner disturbance so, this mattress is great for couples. The foam encasement also helps to eliminate motion transfer, as well.

This mattress has a nice firm feel. It isn't exactly a 'box of rocks' but it does the trick if you're seeking a firm. It has just enough body contouring that you actually feel a bit of the spring unit conforming to your body and, the layers of foam are quite dense and firm. Having a double-sided mattress adds to durability and a longer period of your bed feeling "brand new".

I'd highly recommend this mattress model to anyone seeking a conventional (almost 'old school') firm mattress feel - who likes to get a lot of bang for their buck. No crazy bells and whistles but a lot of support, lots of comfort and a high level of durability. The Symbol "Comfortec" line has cranked out yet another great mattress.

If you're seeking an extra-firm (emphasis on extra), have a look at the Corvina Extra Firm Double-Sided Mattress



  • Shipping or delivery of this item to most areas within the 48 contiguous states only. Delivery of this item to Alaska, Hawaii, US Territories or APO/FPO addresses will require added charges. Please call customer service for rates and availability.
  • Free LTL freight delivery to most cities in the continental US. Destination must be accessible by large truck. Some locations may have a small surcharge.
  • LTL freight service is curbside to your driveway only. White Glove is available for an extra fee.
  • For complete details, read our Shipping and Return policies.



Measure all 4 sides of your mattress and bed frame before ordering.
We recommend you order the mattress 1 inch smaller than the space it is meant to fill. This will leave extra room for sheets, blankets, and variations in production size. Some people like a larger gap to really have room for your hands to reach down and change sheets easily. Please note that production size is not guaranteed to be exact. Most models are built within ±0.5 inches but the difference can be larger, especially on innerspring models. Custom mattresses are hand made by a factory worker who will take a standard mattress, then shorten it to your size. With the way spring coils are shaped, they will not work when cut in half, so an entire row of springs must be removed to modify mattress sizes. As each row is removed, the bed size changes by 1-2 inches, so your bed may not come exactly the size you order.

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Common Questions

What if it doesn't fit?
We will never ship out a mattress that exceeds the size you have ordered without contacting you first to check if the extra size will cause an issue. Since these are custom made for you they can not be returned, so please be careful when taking measurements. On some bed sets, the box spring will be a different size than the mattress so you will need to measure both pieces. Also, since beds are often set up not perfectly square, you will need to measure all four sides of the bed to find the correct size. Be sure to check for boards or bolts that might protrude in to the mattress area and order your pieces small enough to fit inside of these protrusions.
What sizes are available?
Any size is available upon request but with most models you are limited to being smaller than a King mattress. If you need an odd size bigger than a King, here are some models that can be supersized. Please call us to find out what prices would be.
Can I really order any size and shape?
At this time, with only 1 exception (found here), we only distribute 4-sided rectangular mattresses with no special notches cut from the corners. The size can be as large as a king, so up to 76" wide and up to 84" long. If you need an odd size bigger than a king, please call us to find out what models are available. You can also order a custom mattress small enough to fit in a baby's crib. Mattresses are formed by rows of metal springs and since springs cannot work if cut in half, your mattress core will be sized in 1-2 inch increments. This means that if you order 47x63 it will be built between 46x62 to 48x64 but most of the time it will come within 0.5 inches of the requested size. Please let us know how precise your size must be.
What about the box spring?
It is very important to measure the size of your box separate from your mattress because in many older bed sets, the box was made slightly smaller than the mattress. The length and width of solid foundation box springs can be custom made to fit exact dimensions. The thickness can not be customized but boxes are available in several standard thicknesses ranging from 4.5-9 inches.
How soon will my mattress arrive?
Once your order is paid for, a specialist from Michigan Discount Mattress will call you on the phone to verify your sizes and delivery information. Production will begin and usually takes 3-6 days. After production, the mattress will then be packaged at the warehouse within 48 hours to protect it during shipping to your home. Shipping takes 2-8 days depending on the destination city. The combination of producing, packing and delivering means that you should receive your mattress within 1-3 weeks of the day you order. Our streamlined process has successfully delivered 90% of our orders within 3 weeks.