This is a replacement mattress for the one that was purchased at the end of December of 2017. The original one developed lumps in the pillow top with in the first two months of use. It was replaced, after company inspection, with the same mattress at the end of February and now the same thing is happening to the new one. Today I noticed it starting to form an elongated lump starting already after a little more than one month of use. I have already turned the mattress hoping to delay the flaws that this particular model obviously has. It is such a disappointment because not only am I out the money for the cost of the mattress but I chose to go with Serta based on the longevity of the company and prior purchases in the past.