I was concerned about buying a mattress online, especially since I suffer from an autoimmune disease that attacks my musculoskeletal system. I must have a supportive and comfortable bed for a good night's rest; otherwise, I'm in pain all day, and it's hard to function. It is, in fact, 12" and works quite well without a box spring and a platform frame. The mattress comes rolled, and I only had to take it out of the box, unroll it and let it sit. It took about 24 hours to expand fully and about two weeks for the creases to release. This mattress is comfortable and supportive and reduces movement transmission as described. So far, so good.This mattress was excellent. I was scared to buy online but I was wow. I'm a person who suffers a lot of back pain. Yesterday I got tired of my work and I premiered it and my back is more than grateful. The mattress is a little hard but soft. It doesn't take me 15 minutes to deflateI would have given this five star but it's a little more firmer than a medium firm other than it's perfectVery comfortable but this mattress never got to 12in at all, we even waited two extra days to sleep on it, but it is a very nice mattress other than thatWonderful mattress. Sleeps great and helps me not to be stiff in the morningNo se infló completamenteAlthough the mattress didn’t meet my expectations, I was pleased with the customer service of the seller. The customer service is 5 stars.The mattress is comfortable but is off loading gases that smell like fish. We bought the mattress and opened it on Oct 2nd. It stinks up the entire room and is hard to tolerate. We are worried the smell will never leave. This does impact how well you can sleep on it.