Fits my King size Lucid 10 Foam mattress just right, with room to spare, though I doubt it will shift much or anything. I think it could easily fit a thicker mattress. Easy to use, and seems study and washable. This has a stretchy and soft feel to it. Does not feel plastic. It does sound a bit plastic out of the bag, but I dont think it will be an issue under the mattress pad. We have pets and kids so we decided to do an encasement, and additional mattress padprotector just for our sanity.