DC - I still haven’t wrapped my head around the whole thing of how much it will keep bed bugs out. I did buy full encasement ones which zippers the whole mattress into a protector cover. I purchased mine from amazon because it said it fit up to 18" deep mattress. The same brand for the box spring still have not been put on yet. I don’t even know if they will be too big or not. I figure I can tuck any excess in between mattress and box spring. But you can google this to read reviews on amazon:
Zippered Bed-Bug Proof Mattress-Encasement (King)- Water Proof, Protects against Dust Mites, Bacteria, and Allergens - By Utopia Bedding