Purchased a duck feathered mattress topper.
Needed something to soften our new too firm matress. Pros:, soft enough with out waking with lower back pain,..cons: could be more fluffy.
Not sure how long it will last, but great price range around 50$. Excellent service from Wayfair,..will be doing more business  with them.
I would highly recommend  this feathered matress topper, I didn't get down feathers , was looking for a price break, which this has.
No problem getting matress cover over it, & fitted sheet also fit fine over corners.