Hi Bunny1999,
The better topper sources I’m aware of are in the component suppliers list here I linked in my earlier reply about split king mattresses.
There is also more information about choosing a topper in post #2 here and the topper guidelines it links to that can help you use your sleeping experience as a reference point and guideline to help you choose the type, thickness, and firmness for a topper that has the least possible risk and the best chance for success.
I’m looking forward to your comments and feedback about how you like it once you’ve received it.
Phoenix