Hi muncher,
Welcome to the Mattress Forum! 
[quote]It took me a little while to find out who makes it. Solstice Sleep Products.
Very little info on their website and even less info from whoever answers their phones. A sales rep told me they are a new company but had little info other than that.
Does anyone have an opinion on this mattress or company?
Can you make a decision based on their specs?[/quote]
You can see some of my comments about Solstice Sleep Products in post #2 here. Jamison was purchased by Solstice a few years ago.
I don’t have complete confirmed specifications about the Oslo. It seems you’ve found the same specifications on the Wayfair site that I did. My biggest concern would be the density of the 3" of “comfort foam”. You should always make sure that you find out 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.
This mattress is from China, so I would also read post #6 here about mattresses imported from Asia or China and which may have been compressed for long periods of time in either shipping or storage before being purchased, and being sourced in China would make this somewhat of a risky purchase IMO.
Phoenix