Viols are made of wood, and are similar to the violin family. Most viols have six strings, although this number did vary during the centuries. The strings were made of gut, and are not as tight as on a violin. The fingerboard has frets like a guitar, except that they were also made of gut. They were tied around the fingerboard, and could be moved for tuning. These frets help the player to find the exact place to put their fingers. Sometimes the top of the scrolls on the fingerboard were beautifully decorated. The instruments have sloped shoulders and a flat back. The viol, like the vihuela, from which it developed, has a bridge that is flatter than the bridge of a modern violin. This makes it easier to play chords. The bow was convex in shape, where a violin bow is concave.