Advertised as 24cm. After more than 4days of it being open, laid flat in a ventilated room (without being slept on) the max its measured is 21cm. Not ideal (kind of false advertising)  ruins the comfort factor aswell. Feel slightly conned.
Ive tried to get at least a partial refund online but for some reason when clicking the submit refund button its not going through. Will ring Wayfair Customer Service tomorrow and hopefully get it sorted.