Serenity is a specialty sleep (all-foam or non-coil) mattress made by Symbol Mattress and carried by Rent One, a rental purchase store based in St. Louis. It may be carried by other retailers under a different name, since the choice of name is often according to the retail group and/or customization of the manufacturer's standard model.
The closest model currently listed by Symbol Mattress is the St. George Gel and Memory Foam in the Contemporary Series. It is the same height and has the same components, though the relative size of the layers may have been customized (Symbol did not specify layer heights in its descriptions).
The online description of the Serenity says, "Enjoy cooler sleeping." The basis for this claim is gel infused into the 2" top layer of memory foam. This memory foam and that in the next layer down are open-cell foams. This structure lets air filter through the layer to remove heat and moisture. The gel added to the foam absorbs heat.
The second layer is also 2" of memory foam, This time it is labeled "virgin" to show that it does not have the gel. Memory foam is used in this mattress because its conformity to body contours spreads support evenly under the whole body. This supports recessed parts, such as the lumbar, and reduces pressure on larger parts, such as hips and shoulders.
The 9" support core consists of polyurethane foam described as "super dense." This undergirds the softer memory foam. It is there to ensure the sleeper gets adequate support, but with more give than a flat board or the floor.
The Serenity memory foam mattress is available in four sizes: Twin, Full, Queen and King. At Rent One, it is the same price as the Aurora . The Symbol warranty is not stated, but is most likely for 10 years.
Symbol Mattress Serenity
Symbol Mattress Company
Symbol Mattress, PO Box 6689, Richmond, VA 23230, (804) 254-1711, firstname.lastname@example.org
Memory foam with gel
9-inch super dense PU foam support core, 2-inch memory foam, 2-inch gel-infused memory foam,
Provided by the support core
Knit, fabric not specified
Solid top box base, platform bed, or adjustable bed
Open-cell foam for ventilation
Not specified - ask retailer
Prob 10 years NP
Keep in sanitary condition, and provide proper foundation