A sound hole is an opening in the upper sound board of a stringed musical instrument. The sound holes can have different shapes: round in flat-top guitars and traditional bowl-back mandolins; F-holes in instruments from the violin family, archtop mandolins and in archtop guitars; C-holes in violas da gamba, and rosettes in lutes. Bowed lyras have D-holes and mandolins may have F-holes, round or oval holes. A round or oval hole is usually a single one, under the strings. F-holes and D-holes are usually made in pairs placed symmetrically on both sides of the strings. Most hollowbody and semi-hollow electric guitars also have F-holes.