Bass guitar the 3rd, 5th, 7th, 9th fret and 12th fret (the 12th fret being the octave of the open string) and on the octave-up equivalents of the 3rd fret and as many additional positions as an instrument has frets for. Typically, one marker is on the 3rd, 5th, 7th and 9th fret positions and two markers on the 12th fret. The long scale necks on Leo Fender's basses—with a scale length (distance between nut and bridge) of — set the standard for electric basses, although "short scale" instruments, such as the Höfner 500/1 "violin bass" played by Paul McCartney, and the
Guitar frets, which are metal strips (usually nickel alloy or stainless steel) embedded along the fretboard and located at exact points that divide the scale length in accordance with a specific mathematical formula. The exceptions include fretless bass guitars and very rare fretless guitars. Pressing a string against a fret determines the strings' vibrating length and therefore its resultant pitch. The pitch of each consecutive fret is defined at a half-step interval on the chromatic scale. Standard classical guitars have 19 frets and electric guitars between 21 and 24 frets, although guitars have been made with as many as 27 frets.