We purchased this topper to go over our firm, 8âÂÂ king foam mattress. Our goal was to add just a little softness and  reduce the effects of heat retention in the mattress. It is absolutely the best combination I have ever slept on anywhere. Iâve slept in hotels around the world and have owned four different kinds of mattress. Sleeping on this is heaven. 
I chose a down alternative because the last real down topper I purchased had more feathers than down and the feathers all had quills. Ouch. 
The elastics on this topper are positioned really well and everything stays put. Materials and the stitching are all very good quality. We are so pleased with this topper!