Oxen are most often used in teams of two for light work such as plowing. In past days, very large teams of fourteen to twenty oxen were used for heavy work such as logging. The oxen are put into pairs and each pair must work together. A wooden yoke is put about the neck of each pair, so that the work is shared across their shoulders. Oxen are chosen from certain breeds with horns, since the horns hold the yoke in place when the oxen lower their heads, back up or slow down.