Hi Ket2593,
Many of the manufacturers on the list make all latex mattresses but once again the materials in the mattress are more important than the brand. If two mattresses have the same design and materials inside then the name of the manufacturer really makes no difference. Some phone calls will identify which of them have all latex mattresses that you are interested in testing.
You can read more about the different types (Dunlop or Talalay) and blends (natural, synthetic, or a blend of the two) of latex in post #6 here.
Post #21 here also has a list of the online manufacturers that are members of this site and many of them also sell all latex mattresses in a wide range of designs.
Phoenix