I got this because I have a 14" mattress and wanted to try a 5" feather bed topper for my back. It's survives a few wash cycles and stayed waterproof and I tested it after first putting it on from unboxing and it did repel an entire cup of liquid without staining. This thing easily handles all 19" of depth and actually can tuck in and stay on within reason. It's staying on when my bed sheets are long gone from my active sleeping or something else without the protector having bed suspenders or grippers of any kind. I use Gorilla grip on my feather bed and grippers on my sheets that don't stay on as well as it does.
This applies to any brand and what happened to my last one that was inferior to depth compared to this one. I use this to protect the memory foam and now also a feather bed from staining, sweat, or anything else. It will eventually run out of it's waterproof material I am assuming and it's better to sleep on this with a washable mattress pad that cools or really nice bed sheets as too thin will easily collect sweat.