I bought the medium form king single mattresses for my two kids aged 5&6, these mattresses are solid, thick, warm, comfy inventions that I hope will last them till they are adults. The mattresses aren't cheap but I took a punt based on the online reviews (and their 100 day money back promise) and I am very happy. Mattresses are an investment in health and they're also a pain to dispose of so I wanted a mattress to last. Also very much love the compressed box they get delivered in as it's so much easier to position the mattress in the room before opening!
My last matters was some cheap clearance mattress that lasted maybe a year and looked and felt like a sack stuffed with metal. The mattress started to give me neck, shoulder and lower back pain as well the second anyone got on the bed with me it dipped so low in the middle it almost hit the ground.
I wad recommended sleeping duck from my best friend and I have to say I owe him and the sleeping duck team a great deal of thanks. After about a fortnight with sleeping duck all aches and pains we're gone and my sleep was more consistent and comfortable. I could go on and on about the miracle of sleeping duck and a few other things its improved (hehe) but I'd be going in ciricles at that point.
Sleeping duck 11/10 give them your money. There mattress are literally life changing that's how good they are. One of the best choices I've made in my life.