Hi MIke407 .
OMF makes primarily two-sided mattresses and they are one of the better quality and value regional manufacturers. You can see a few examples of the construction of their mattresses in post #32 here. Some of their pillowtops use some very high-quality HR polyfoam which can be a very durable and long lasting material that approaches latex in some of its performance specs.
I am guessing that you are looking at their (14.5") Ultra Plush Set. They don’t list the materials used in the comfort layers on their site but from my past experience, they are transparent about the quality of the materials in their mattresses which is one of the most important parts of shopping for a mattress. They also use higher quality materials in their lineup than most larger brands but you would need to contact them and ask the specifics of each layer as outlined in the information listed here so you can compare the quality of the materials and components to the durability guidelines here to make sure there are no lower quality materials or weak links in a mattress that would be a cause for concern relative to the durability and useful life of a mattress before making any purchase.
I’d also take into account SweetDreams note that OMF does not accept returns or exchanges so you’d need to make sure that what you order meets your comfort/support needs or consult their Comfort policy here.
Phoenix