A crucial element in playing the horn deals with the mouthpiece. Most of the time, the mouthpiece is placed in the exact center of the lips, but, because of differences in the formation of the lips and teeth of different players, some tend to play with the mouthpiece slightly off center.[4] Although the exact side-to-side placement of the mouthpiece varies for most horn players, the up-and-down placement of the mouthpiece is generally two-thirds on the upper lip and one-third on the lower lip.[4] Usually, in order to play higher octave notes, the pressure exerted on the lips from the mouthpiece is increased. But, although some pressure is needed, excessive pressure is not desirable. Playing with excessive pressure makes the playing of the horn sound forced and harsh as well as decreases endurance of the player by about half