A bosal (//, //, or //) is a type of noseband used on the classic hackamore of the vaquero tradition. It is usually made of braided rawhide and is fitted to the horse in a manner that allows it to rest quietly until the rider uses the reins to give a signal. It acts upon the horse's nose and jaw. Though seen in both the "Texas" and the "California" cowboy traditions, it is most closely associated with the "California" style of western riding. Sometimes the term bosal is used to describe the entire classic hackamore or jaquima. Technically, however, the term refers only to the noseband portion of the equipment.
Bosals come in varying diameters and weights, allowing a more skilled horse to "graduate" into ever lighter equipment. Once a young horse is solidly trained with a bosal, a bit is added and the horse is gradually shifted from the hackamore to a bit.