Variable beds, also known as Semi-Fowler furniture, can be adjusted in position to suit the prerequisites of the user. Those who have health concerns that require them to sleep in some positions generally use adjustable beds. They may be also used by those who are temporarily or permanently bed-ridden to make them sleep more comfortably. Sometimes, even those without medical requirements can use adjustable beds to have a comfortable sleep. Changeable beds can be altered in a comfortable position as per the sleeper's requirements. They are very comfy for reading or pertaining to watching TV in bed. They are also perfect for people who have bad sleeping problems due to stress, body strain or other discomforts. Because the adjustable beds is usually molded according to the person's physiology, they provide utmost comfort and rest. Adjustable beds are also very strong and can support weights in excess of 600 pounds. Adjustable beds are made in two models: standard or heavy-duty. Flexible beds are comprised of two main components: the base plus the mattress. There are several features to be considered while buying an adjustable bed: the size of the mattress (twin, queen, king or full) and the type of mattress (foam, latex, coil spring or simply air). Ordinary mattresses cannot be used on adjustable beds. The mattresses for adjustable furniture are also specially designed to suit the human body. This helps to relieve stress on certain parts of the body and proper spinal alignment. They are also forwarded to adjustable rails on both side.