Hey sleepseeker2021,
Thanks for your question 
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Thanks for including the West Elm site link, sleepseeker. I took a peek at their exclusive DUX Mattress model and found the specs to be vague, no specifics on type latex, ILD firmness, coil gauges, etc. Duxiana is well-known for their proprietary continuous coil systems, as well as their patented “Pascal” cassettes designed for customizing support zones underneath its zippered top layer. This particular DUX model doesn’t use the Pascal cassettes but has a two-layer coil design, with a 2.5" latex comfort layer. I used their chatbot to ask what type latex and ILD are used, but the reply was from their Design support team and offered this number for product knowledge discussions, you may want to check it out: 1-888-922-4119.
There are many posts on all three of these brands in the forum’s history, you may try a site search to see which ones may be helpful in your research. I’ve been following consumer feedback on your other posttoo, you’ve gotten good response there. Hopefully, someone who has personal experience with Duxiana, Hastens, or Vispring will drop by and offer their thoughts. Good luck with your research and let us know which way you decide to go.
Sensei 