I bought this mattress along with a twin of another brand, for my girls bunk bed. One is 12 and adult sized so, I went with a 12 inch memory foam. Within 5 minutes of removing it from the box, the mattress expanded to the full 12 inches. I also bought her a memory foam pillow. She hasn't left her bedroom since. We recieved the other mattress today. After 10 hours it's not looking good.