<P> In Europe, wooden frames with a middle section consisting of springs held in place by wire (to be put into the wooden bedframe as a unit) used to be the standard for most of the 20th century . The springs have mostly been replaced by pre-bent wooden slats (usually glulam made from beech or birch) which are joined to the outer wooden frame by some form of flexible rubber bolt, shoe or socket . This lath floor provides suspension, allows the mattress to ventilate, and can be designed to be vertically adjustable in order to elevate the legs and / or the torso . A more simple approach is to join straight laths with a textile strap so that they can be rolled up for transport and placed right into the bedframe . </P> <Table> <Tr> <Td> </Td> <Td> Wikimedia Commons has media related to Box - spring . </Td> </Tr> </Table> <Tr> <Td> </Td> <Td> Wikimedia Commons has media related to Box - spring . </Td> </Tr>

Which side of the box spring is the top