The violin's cornered, hourglass-shaped body is made up of several pieces of wood. The top and bottom of the carved carcass are fairly thick; the front plate, also known as the belly, is made from fine-grained spruce and is of an even thickness - around 3mm, though that varies depending on the maker and the qualities of the wood. A pair of soundholes, known as 'f' holes because of their shape, are cut into the lower part of the belly. The back plate is nearly always made from flamed maple - which in fact is sometimes known as 'fiddleback maple' for this reason. It varies in thickness, being thinner around the sides and thicker in the middle. The sides, or ribs are made of six thin pieces: the upper bouts form the shoulders of the violin, the 'C' bouts form the waist and the lower bouts, occasionally formed from a single long strip instead of two, curve round to meet at the bottom. They are usually made of flamed maple, which is steamed and bent to a form, then allowed to dry until the form keeps (adheres). The ribs are reinforced at the joins by blocks of wood and