Hi wacomme,
The help tab here has more information about searching the site that should be helpful.
There is more information about Foamsource in this topic and a forum search on foamsource (you can just click the link) will bring up more comments and feedback about them as well.
They specialize in latex mattresses (although they have a memory foam mattress as well) that use a range of different types and blends of latex that have different designs and custom firmness options and they have a 60 day comfort exchange policy as well so you can change the comfort or support of your mattress after a purchase.
All of their mattresses use high quality materials and there are no lower quality materials or weak links in any of them.
Phoenix