I was a bit worried this wouldn't protect my child's king single enough so I purchased the double as well as the single/KS. It fits really well, with about 1cm waterproof liner extending past both sides of the mattress.
I find they hang dry fast after washing (it is summer but even on cooler days).
It's quiet (unlike PVA type waterproof protection) and the colours are just as vibrant in person.
Great for my tactile, thermal, auditory sensitive child.
I just hope the KS fitted sheet in the Under the Sea pattern becomes available asap as I particular love that I can use liners which are the same pattern as the sheet for my Autistic child so they are less obvious to peers or situations they may be embarrassed to be using liners.