There are also some rare specimens that were built with an oval body. Head The head or "headstock" is located at the end of the guitar neck farthest from the body. Modern instruments are fitted with machine head tuners, though older instruments (particularly from the 19th century) have friction pegs. The tuner layout is usually in one of two forms: "4+3", with four tuners on the bass-string side of the head and three on the treble string side; or "3+1+3", with three tuners on each side of the headstock and one in the middle. The nut is a small strip traditionally of bone, but plastic, brass, and other materials are also sometimes seen. Neck Headstock, fingerboard (fretboard), and truss rod (if present), all attached to a long wooden extension which collectively constitutes the neck. The wood used to make the fretboard usually differs from the wood in the rest of the neck. The neck joint or heel is the point at which the neck is attached to the body of the guitar. Fingerboard The fingerboard is made of hardwood (ebony or rosewood are common), fitted with metal frets of brass or steel. Fret spacing almost always follows the western twelve tone equal temperament (12-tet) system. The surface of the fingerboard may be flat or curved slightly ("radiused"), although the radius of a curve on the Russian guitar is usually somewhat less than that of an equivalent western 6-string guitar. Inlayed position markers are common, and appear in the same locations as 6-string guitars (e.g., typically the 5th, 7th, 9th, and 12th frets, among others). Body The sound board is usually made of spruce or cedar, and sized and shaped much like that of the 6-string guitar. Overall proportions of classical seven string instruments nylon string) are similar to those of 6-string guitars. "Gypsy" instruments (steel string) may be proportioned similarly, but also may often feature a narrower upper bout, and an enlarged sound hole. Both traditionally shaped instruments and instruments with cut-away bodies are available. The bridge is made of a hardwood similar to that used for the fingerboard, and the bridge saddle is usually bone or sometimes plastic; on old instruments, ivory was sometimes used. A pickguard, or "scratchplate"—usually a piece of laminated plastic—is frequently found on steel-string "gypsy" instruments; on nylon-string classical instruments it is usually lacking. Strings As noted above, Russian guitars may have either nylon (or