Indicates the main composition of the mattress, such as innerspring or memory foam. Some so-called "hybrid" innersprings include one or more levels of foam on top.

If you’re looking for a replacement, over 5,200 Walmart shoppers swear by these never-flat Serta pillows that are just $9.

The best part? That’s not the only sale Serta is hosting. In addition to Presidents Day discounts, the mattress brand is ...