Never-slept on Slumberfy Bamboo Mattress Encasement, for 9-12" deep king-size mattress. Never slept on: only took out of box to size up against their 12-15" size (which I bought, and still sleep on). Retails $70 at Amazon: see details and reviews here.
https://www.amazon.com/Slumberfy-Zippered-Mattress-Encasement-9/dp/B08T6BLBHG/ref=asc_df_B08T6BLBHG/?tag=hyprod-20&linkCode=df0&hvadid=563537347563&hvpos=&hvnetw=g&hvrand=13798716662199713024&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9028727&hvtargid=pla-1625144961324&psc=1&mcid=d0356357868a3d1382acad9cbe814c51