The French horn has a 4½-octave range, with 3 octaves commonly used in the horn repertoire. That wide range means horn composers must use both bass and treble clefs when writing for horns. In many orchestral arrangements, the higher first and third horn parts are written in treble clef while the lower second and fourth parts use bass clef. In addition to knowing how to sight-transpose into different keys, a skilled horn player must also read music in both bass and treble clef.