We have had a King-size firm mattress for a few years now, and struggle to sleep on anything else. So when our little one was ready to move into a big bed it was a no-brainer to get a King-Single Sleeping Duck for her too. Needless to say her elder siblings are very jealous, and she sleeps like a log.
I bought the single mattress for my 9yr old son, however while the mattress is undeniably comfortable, he does become quite hot.
Bought this mattress for our growing teenager. He's never been more comfortable and the king size single gives him plenty of scope for growth.