When you are speaking about memory foam mattresses you are talking about a type of foam mattress that was invented by NASA in 1966 and the original purpose of this foam which is also known as visco-elastic was to improve the safety of aircraft cushions. It is basically polyurethane with additional chemicals added to it. It has an overall cell structure intended to increase density and viscosity especially when a human body is in contact with it. This memory foam was released for general public use in the early 80s and this is when certain companies began to experiment with it and make a mattress from this material.
A memory foam mattress can be either high density or low density. High density will be softer in reacting to body heat and it will mold to the body within minutes and when the heat is removed it returns to its original form and shape. High density foam has a longer lifespan than low density memory foam does so it is the more expensive memory foam mattress. The low density foam is pressure sensitive and molds to the body under pressure then it returns to its original form when the pressure is released. These foam mattresses come in various thicknesses.
This particular foam mattress will be denser than other foam materials so it will be a heavier mattress in weight. This type of mattress is good because when your body molds into the mattress you actually are relieving pressure points on the body giving you a more comfortable sleep. Generally the thicker the foam the more the body will sink into it. But these are generally three to four inches thick whereas the higher quality and more expensive ones may be over four inches thick. They also are sold with a no turn feature which means you never have to turn over the mattress again. They have an expected lifespan of ten to twenty years.
If this is the type of mattress you are looking for then you can expect to pay more for it than you would pay for a more traditional box spring and innerspring mattress. There are pros and cons to each type of mattress. Some innerspring mattresses use a combination of this foam and other materials to make up the mattress but it will not be totally from this visco-elastic material. These mattresses made from visco-elastic materials are also supposed to be hypo-allergic and anti microbial too. Some people think they get too hot because they do respond to your natural body heat. But again people have many different opinions regarding any type of mattress.
When you are looking for a new mattress you have many choices from a foam mattress to a traditional mattress to an airbed or even a water bed. What you choose will depend on your sleeping requirements, your budget and the space you have available to fit in the mattress. It may also simply depend on what size sheets you already own.