Hi cownox,
The only way to know the quality or value of any mattress is by knowing what is inside it.
Solstice Sleep Products (aka Associated Bedding Co) is a Columbus based wholesale manufacturer (with a factory in Florida as well) but as you mentioned their website doesn’t provide any information about the quality of the materials. The materials inside a mattress is always more important than the name on a label.
Unless you have no other options … I would want to know the details of all the layers of a mattress I was considering so you can make some kind of meaningful assessment of its quality and value and durability.
There are some specs which indicate that at least this mattresses is using low quality/density 3.2 lb memory foam which I would tend to avoid and most retailers would consider the Solstice mattresses to be their lower end or “promotional” mattresses.
It seems like you are somewhat “trapped” in making exchanges with what sounds like a liquidator who has a somewhat “random” selection of mattresses and who doesn’t seem to know where their mattresses come from, what is in them, or who may have used them but this is just part of the risk of working with a liquidator in exchange for “cheap” prices.
Since their mattresses may be used, returns, floor models, or comfort exchanges … post #2 here may be helpful for things you may want to check for (at least the parts that you can because you may not be able to check inside) before buying any of their mattresses.
Phoenix