The mattress arrived on time and we let it set for 48 hours and it puffed up to the 10”. The mattress looked funny like it was deformed for the first 10 to 12 hours, but kept growing and filling out slowly and we let it just sit on top of our spare room bed to get fully expanded. Slept on it last night and felt wonderful. No sore back in the morning. Firm enough for the back but still very comfy with a little give. This is the third Wayfair Sleep Memory Foam mattress we have bought. Had one in MI and one in our spare bedroom here in AZ. Wouldn’t have bought a third one if we didn’t like them.